Astronomy

Disk-integrated vs disk-resolved, what is the difference?

Disk-integrated vs disk-resolved, what is the difference?


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I'm trying to find online what is the difference between disk-integrated vs. disk-resolved, but I can't find a website which does explain them, especially in the context of modelling spectral flux density. Also, since the word disk is being used, it is only applicable to spherical planetary bodies? Is spatially-resolved and disk-resolved the same thing?

Source


The way disk-integrated and disk-resolved is used in your cited paper is nothing special, just indicating optical resolving power in relation to the image of the object of interest:

With a disk-integrated signal they mean a single value as measured over the whole disk (of an image a planet makes - or whatever is imaged as a disk).

When they talk about disk-resolved data, they mean that they have a large enough image of the planet they image so that they can start to discover regional inhomogeneity of the signal, thus make out different regions with different properties.

So the distinction is just that of a spatial resolution: either you can resolve the object of interest and see surface (or cloud) structures (disk-resolved). Or your signal is too faint, your optics too small, and you just get spatially unresolved data, thus disk-integrated over the image of the disk, the whole planet (thus you cannot distinguish anything based on location on the planet - you just measure overall albedo, spectral properties etc)


What Is a Storage Array? Data Server and Disk Architecture

A storage array, also called a disk array, is a data storage system for block-based storage, file-based storage, or object storage. Rather than store data on a server, storage arrays use multiple drives in a collection capable of storing a huge amount of data, managed by a central management system.

The performance of storage arrays can be improved by using a high-quality management system to keep track of capacity, errors, and trends. In this guide, I discuss the basics of storage arrays, including what they are, how they work, common setups of data centers, and how monitoring tools can help improve array performance. I also review the key features of several of these top solutions, and explain why Storage Resource Monitor is my best pick due to its unified management system, performance optimization capabilities, and storage capacity forecasting features.


SOLAR SYSTEM | Jupiter, Saturn and Their Moons

Callisto

Callisto is rather smaller than Ganymede, and is less dense, so that ice is a major constituent of the globe. The surface is heavily cratered, and there are two huge ringed plains, Valhalla and Asgard. Unexpectedly, it has been found that the local magnetic field fluctuates in the same way as that of Europa, and there may be a similar salty ocean deep inside the globe. Space-craft data indicate that the interior of Callisto is made up of compressed rock and ice, with the percentage of rock increasing with depth.


An Overview of HDD

HDD stands for hard disk drive. It is a kind of traditional storage device for personal computers. It is developed based on rotating magnetic platters and reading heads. Compared with other drives, HDDs are characterized by longer system boot-up times, slower application and file loading, as well as slower files copy and paste command execution.

Generally speaking, the standard rotational speed of platters is 5400 rounds per minute (rpm). HDDs in high-end notebook spin at 7200rpm, which improves the writing, reading, and data accessing speed.

Nevertheless, 7200rpm HDD is rare on the market. Besides, it won’t have obvious performance improvement. The size of HDD’s cache memory (usually is 8MB or 16MB) also affects the performance of a laptop.

Though HDDs have so many drawbacks, they have some strengths too. The hard disk drive is the cheapest one compared with other drives such as SSD, hybrid drive, and eMMC. Additionally, HDDs can hold a large amount of data.

Now that you have learned the basics of the two drives, it’s time to compare them and then choose a suitable one for your laptop.

Main Differences between eMMC and HDD


SSD vs. HDD: Speed

What makes SSDs an increasingly popular choice is their speed. Across the board, SSDs outpace HDDs because they use electrical circuitry and have no physical moving parts. This leads to shorter wait times when you&rsquore starting up and fewer delays when opening apps or doing heavy computing tasks. For example, the Intel SSD D5-P5316 is a 15.36TB enterprise-grade SSD that offers over 7000 MB/s in bandwidth. The 14TB Seagate Exos 2x14, a compatible HDD, offers only up to 500 MB/s in bandwidth. That&rsquos a difference of 14x! 1

These faster speeds lead to performance benefits in several areas, such as when logging in and waiting for apps and services to start up, or when performing storage-intensive tasks such as copying a large file. With an HDD, performance slows significantly, while an SSD can continue to work on other tasks.

Speed is also influenced by the interface used in an SSD vs. HDD that connects to the rest of the computer system when transferring data back and forth. You might have heard of these interfaces&mdashSATA and PCI Express (PCIe). SATA is an older, slower, legacy technology, while PCIe is newer and faster. SSDs with PCIe interfaces will typically be much faster than HDDs with SATA because PCIe contains more channels to transfer data. Think of it like the number of cars that can go down a one-lane country road compared to a four lane highway.

Although no one ever complains that their computer is too fast, there are times when an HDD can make sense. If you have terabytes of files that you want to store, HDDs are still a less expensive option, although that&rsquos changing with increasingly lower SSD prices and newer NAND technologies driving bit densities higher per NAND die. Computer storage decisions can be simplified by thinking of data as either cold or hot. &ldquoCold&rdquo data might include the years of photos you want to keep on your laptop but don&rsquot look at every day and don&rsquot need quick access to. HDDs can be an excellent, cost-effective choice for cold data. At the other end of the spectrum, if you&rsquore a business running real-time transactions, editing videos and photos and need fast access to a database of files, video clips, or models, or even just running the operating system, that&rsquos referred to as &ldquohot&rdquo data. The fast performance of SSDs makes them an ideal choice for when speedy access to your data is what matters most.


Contents

Invented by Lovecraft in 1928, the name Cthulhu was probably chosen to echo the word chthonic (Classical Greek "of the earth"), as apparently suggested by Lovecraft himself at the end of his 1923 tale "The Rats in the Walls". [3] The chthonic, or earth-dwelling, spirit has precedents in numerous ancient and medieval mythologies, often guarding mines and precious underground treasures, notably in the Germanic dwarfs and the Greek Chalybes, Telchines or Dactyls. [4]

Lovecraft transcribed the pronunciation of Cthulhu as Khlûl′-hloo, and said, "the first syllable pronounced gutturally and very thickly. The 'u' is about like that in 'full', and the first syllable is not unlike 'klul' in sound, hence the 'h' represents the guttural thickness" [5] (see the discussion linked below). S. T. Joshi points out, however, that Lovecraft gave several different pronunciations on different occasions. [6] According to Lovecraft, this is merely the closest that the human vocal apparatus can come to reproducing the syllables of an alien language. [7] Cthulhu has also been spelled in many other ways, including Tulu, Katulu, and Kutulu. [8] The name is often preceded by the epithet Great, Dead, or Dread.

Long after Lovecraft's death, Chaosium, publishers of the Call of Cthulhu role-playing game, influenced modern pronunciation with the statement, "we say it kuh-THOOL-hu", even while noting that Lovecraft said it differently. [9] Others use the pronunciation Katulu or Kutulu or / k ə ˈ t uː l uː / [10]

In "The Call of Cthulhu", H. P. Lovecraft describes a statue of Cthulhu as "A monster of vaguely anthropoid outline, but with an octopus-like head whose face was a mass of feelers, a scaly, rubbery-looking body, prodigious claws on hind and fore feet, and long, narrow wings behind." [11] Cthulhu is said to resemble an octopus, a dragon, and a human caricature, hundreds of meters tall, with webbed, human-looking arms and legs and a pair of rudimentary wings on its back. [11] Its head is depicted as similar to the entirety of a gigantic octopus, with an unknown number of tentacles surrounding its supposed mouth.

The short story that first mentions Cthulhu, "The Call of Cthulhu", was published in Weird Tales in 1928, and established the character as a malevolent entity, hibernating within R'lyeh, an underwater city in the South Pacific. The imprisoned Cthulhu is apparently the source of constant subconscious anxiety for all mankind, and is also the object of worship, both by a number of human cults (including in New Zealand, Greenland, Louisiana, and the Chinese mountains) and by other Lovecraftian monsters (called Deep Ones [12] and Mi-Go [13] ). The short story asserts the premise that, while currently trapped, Cthulhu will eventually return. His worshippers chant "Ph'nglui mglw'nafh Cthulhu R'lyeh wgah'nagl fhtagn " ("In his house at R'lyeh, dead Cthulhu waits dreaming."). [11]

Lovecraft conceived a detailed genealogy for Cthulhu (published as "Letter 617" in Selected Letters) [1] and made the character a central reference in his works. [14] The short story "The Dunwich Horror" (1928) [15] refers to Cthulhu, while "The Whisperer in Darkness" (1930) hints that one of his characters knows the creature's origins ("I learned whence Cthulhu first came, and why half the great temporary stars of history had flared forth."). [13] The 1931 novella At the Mountains of Madness refers to the "star-spawn of Cthulhu", who warred with another race called the Elder Things before the dawn of man. [16]

August Derleth, a correspondent of Lovecraft's, used the creature's name to identify the system of lore employed by Lovecraft and his literary successors, the Cthulhu Mythos. In 1937, Derleth wrote the short story "The Return of Hastur", and proposed two groups of opposed cosmic entities:

the Old or Ancient Ones, the Elder Gods, of cosmic good, and those of cosmic evil, bearing many names, and themselves of different groups, as if associated with the elements and yet transcending them: for there are the Water Beings, hidden in the depths those of Air that are the primal lurkers beyond time those of Earth, horrible animate survivors of distant eons. [17] : 256

According to Derleth's scheme, "Great Cthulhu is one of the Water Elementals" and was engaged in an age-old arch-rivalry with a designated air elemental, Hastur the Unspeakable, described as Cthulhu's "half-brother". [17] : 256, 266 Based on this framework, Derleth wrote a series of short stories published in Weird Tales (1944–1952) and collected as The Trail of Cthulhu, depicting the struggle of a Dr. Laban Shrewsbury and his associates against Cthulhu and his minions. In addition, Cthulhu is referenced in Derleth's 1945 novel “The Lurker at the Threshold” published by Arkham House. The novel can also be found in “The Watchers Out of Time and Others”, a collection of stories from Derleth's interpretations of Lovecraftian Mythos published by Arkham House in 1974.

Derleth's interpretations have been criticized by Lovecraft enthusiast Michel Houellebecq, among others. Houellebecq's H. P. Lovecraft: Against the World, Against Life (2005) decries Derleth for attempting to reshape Lovecraft's strictly amoral continuity into a stereotypical conflict between forces of objective good and evil. [18]

In John Glasby's "A Shadow from the Aeons", Cthulhu is seen by the narrator roaming the riverbank near Dominic Waldron's castle, and roaring. [ citation needed ] The god appears totally different from its depiction by other authors. [ citation needed ]

The character's influence also extended into gaming literature games company TSR included an entire chapter on the Cthulhu mythos (including statistics for the character) in the first printing of Dungeons & Dragons sourcebook Deities & Demigods (1980). TSR, however, were unaware that Arkham House, which asserted copyright on almost all Lovecraft literature, had already licensed the Cthulhu property to game company Chaosium. Although Chaosium stipulated that TSR could continue to use the material if each future edition featured a published credit to Chaosium, TSR refused and the material was removed from all subsequent editions. [19]

Games Edit

In 1981, Chaosium released their role-playing game Call of Cthulhu. This game may have greatly contributed to making the works of Lovecraft known to a bigger audience. It has now reached its seventh edition with a large amount of supplementary material also available, and has won several major gaming awards. In 1987, Chaosium published the co-operative adventure board game Arkham Horror, based on the same background, which has since been reissued by other publishers. In 1996, they released a collectible card game, Mythos.

In 2004, Fantasy Flight Games began a long-term relationship with Chaosium and released a collectible card game, which has been remarketed in a new format (living card game) in 2008 as Call of Cthulhu: The Card Game. This was the first of a collection of games by this publisher, and the only one in its family that was not co-operative. The company have followed since a fully rebuilt Arkham Horror (2005, 2018), the dice game Elder Sign (2011), the dungeon (or mansion) crawler Mansions of Madness (2011, 2016), a pulp version of Arkham Horror with Eldritch Horror (2013), a storytelling living card game Arkham Horror: The Card Game (2016), and a deduction game Arkham Horror: Final Hour (2019). [20]

In 2006, Bethesda Softworks, Ubisoft, and 2K Games jointly published a game by Headfirst Productions, Call of Cthulhu: Dark Corners of the Earth, based on the works of Lovecraft. Cthulhu himself does not appear, as the main antagonists of the game are the Deep Ones from The Shadow Over Innsmouth, and the sea god Dagon, but his presence is alluded to several times, and viewing a statue of him in one of the temples will undermine the player's sanity. Also, one of Cthulhu's Star Spawn, of similar hideous appearance, appears as a late-game enemy. [21]

On March 19, 2007, Steve Jackson Games released an iteration of their card game Munchkin called Munchkin Cthulhu. [22] The game presents Cthulhu and its surrounding mythos with a cartoon-art style and comedic tone, heavily playing upon themes of madness and cultism. Great Cthulhu features as a standalone monster in the deck, alongside various parodies of Lovecraft's creatures. [23] Cthulhu is depicted as an overweight, bright green creature with a large, bulbous head, and a pair of disproportionately small wings. [24]

The Ukrainian video game series S.T.A.L.K.E.R. has a Cthulhu-inspired mutant called Bloodsucker.

Cthulhu is the main inspiration for the zombies in the video game Call of Duty: Black Ops 3. [25]

The massively multiplayer online role-playing game World of Warcraft has numerous references to Cthulhu and the Mythos, including an early raid boss called C'Thun, and more recently, one of the game's "Old Gods" named N'Zoth resting in a sunken city. [26]

In Scribblenauts (2009), Cthulhu is summonable. He is much smaller than described in Lovecraft's works, but is much stronger than most other aggressive objects.

Cthulhu Saves the World (2010) features Cthulhu in the unusual role of protagonist. A prequel, Cthulhu Saves Christmas, was released in 2019.

Terraria (2011) refers to Cthulhu in three boss fights: Eye of Cthulhu, Brain of Cthulhu, and the final boss Moon Lord, implied to be Cthulhu's brother, or possibly Cthulhu himself. [27] [ better source needed ]

In 2013, Treefrog Games released A Study in Emerald, a board game based upon a short story written by Neil Gaiman that blends Cthulhu Mythos and Sherlock Holmes. [28]

In 2015, the author of Chaosium's 1981 role-playing game, Sandy Petersen, designed an asymmetrical board game: Cthulhu Wars.

In the 2015 video game Bloodborne, game director Hidetaka Miyazaki decided to incorporate ideas and themes from Lovecraft's novels such as creatures based on Lovecraft's Great Old Ones. [29]

In 2016, Z-Man Games released an alternate version of the board game Pandemic. This new adaptation, Pandemic: Reign of Cthulhu, is set in the Cthulhu Mythos and explorers race to save the world before Cthulhu returns. [30]

In the 2016 Android video game Flappy monsters of Lovecraft, a flappy style game, players can take control of Cthulhu.

In 2018, a survival horror role-playing video game called Call of Cthulhu: The Official Video Game was developed for PlayStation 4, Xbox One, and Windows PC.

On 2 April 2018, an asymmetrical survival horror video game called Identity V was launched by NetEase. The game includes hunter characters from Cthulhu Mythos. The game can be played through both mobile and PC.

In 2019, CMON Limited released the board game Cthulhu: Death May Die.

In June 2019, an open-world horror detective game called The Sinking City, which is based on Cthulhu Mythos, was released for Microsoft Windows, PlayStation 4, and Xbox One. It was also released for Nintendo Switch in September of that year.

On December 10 of 2019, first-person shooter and survival horror Killing Floor 2, released a seasonal update titled Yuletide Horror, which included a map named Sanitarium with an Easter egg revealing the appearance of Cthulhu in the background. [31] [32]

In 2020, Cthulhu was released as a playable character in the MOBA Smite.

Politics Edit

Cthulhu has appeared as a parody candidate in several elections, including the 2010 Polish presidential election and the 2012 and 2016 US presidential elections. [33] [34] The faux campaigns usually satirize voters who claim to vote for the "lesser evil". In 2016, the troll account known as "The Dark Lord Cthulhu" submitted an official application to be on the Massachusetts Presidential Ballot. The account also raised over $4000 from fans to fund the campaign through a gofundme.com page. Gofundme removed the campaign page and refunded contributions. The Cthulhu Party [35] (UK), another pseudo-political organisation, claim to be 'Changing Politics for Evil', parodying the Brexit Party's 'Changing Politics for Good' a member of The Cthulhu Party holds the position of Mayor of Blists Hill. Another organization, Cthulhu for America, ran during the 2016 American presidential election, drawing comparisons with other satirical presidential candidates such as Vermin Supreme. [36] The organization had a platform that included the legalization of human sacrifice, driving all Americans insane, and an end to peace. [37]

Science Edit

The Californian spider species Pimoa cthulhu, described by Gustavo Hormiga in 1994, [38] and the New Guinea moth species Speiredonia cthulhui, described by Alberto Zilli and Jeremy D. Holloway in 2005, [39] are named after Cthulhu.

Two microorganisms that assist in the digestion of wood by termites have been named after Cthulhu and Cthulhu's "daughter" Cthylla: Cthulhu macrofasciculumque and Cthylla microfasciculumque. [40]

In 2014, science and technology scholar Donna Haraway gave a talk entitled "Anthropocene, Capitalocene, Chthulucene: Staying with the Trouble", in which she proposed the term "Chthulucene" as an alternative for the concept of the Anthropocene era, due to the entangling interconnectedness of all supposedly individual beings. [41] Haraway has denied any indebtedness to Lovecraft's Cthulhu, claiming that her "chthulu" is derived from Greek khthonios, "of the earth". [42] However, the Lovecraft character is much closer to her coined term than the Greek root, and her description of its meaning coincides with Lovecraft's idea of the apocalyptic, multitentacled threat of Cthulhu to collapse civilization into an endless dark horror: "Chthulucene does not close in on itself it does not round off its contact zones are ubiquitous and continuously spin out loopy tendrils." [43]

In 2015, an elongated, dark region along the equator of Pluto, initially referred to as "the Whale", was proposed to be named "Cthulhu Regio", by the NASA team responsible for the New Horizons mission. [44] It is now known as "Cthulhu Macula". [45] [46]

In April 2019, Imran A. Rahman and a team announced in Proceedings of the Royal Society B the discovery of Sollasina cthulhu, an extinct member of the ophiocistioids group. [47]

Film and TV Edit

Several films and television programs feature the threat of Cthulhu returning to dominate the Universe. A notable example is three episodes of the adult cartoon series South Park in which Eric Cartman turns out to be so irredeemably evil that he is able to tame Cthulhu and direct him to annihilate personal enemies. [48] In those episodes ("Coon 2: Hindsight", "Mysterion Rises", and "Coon vs. Coon & Friends") Cthulhu is faithfully represented as the monstrous tentacle-mouthed god-like being Lovecraft describes. [48] In the popular adult animated science-fiction sitcom Rick and Morty, a depiction of Cthulhu can be seen in the opening sequence, immediately prior to the title card. [49] In Cartoon Network's animated show The Grim Adventures of Billy and Mandy, Cthulhu has a dedicated double-length episode called "Prank Call of Cthulhu". Cthulhu also made a short appearance at the beginning of The Simpsons episode "Treehouse of Horror XXIX".

In the Justice League animated series episode "The Terror Beyond" under Warner Bros, Cthulhu is shown as an invader from an interdimensional world to earth where Justice League team members fight with Cthulhu. In season two, episodes 18 and 19 of Gravity Falls, Cthulhu is briefly seen destroying a giant ear with a mouth-laser and then walking, respectively. [50] [51]

On October 27, 1987, Cthulhu appeared in season two, episode 28 of The Real Ghostbusters animated cartoon entitled "The Collect Call of Cathulhu", in which the Ghostbusters went up against the Spawn, and Cult, of Cthulhu. [52]

Cthulhu is featured in Arcana Studio's Howard Lovecraft animated trilogy beginning with Howard Lovecraft and the Frozen Kingdom, and ending with the upcoming Kingdom of Madness. [53] [54]

The Call of Cthulhu is a 2005 independent silent-film adaptation of the eponymous short story, produced by Sean Branney and Andrew Leman. [ citation needed ]

Cast a Deadly Spell is a 1991 noir film featuring private detective H. Philip Lovecraft, in a fictional Los Angeles, where magic is real, monsters and mythical beasts stalk the back alleys, zombies are used as cheap labor, and everyone—except Lovecraft—uses magic every day. The plot revolves around a scheme to use a copy of the Necronomicon to summon an ancient god that might be Cthulhu. [ citation needed ]

The 2007 film Cthulhu is loosely based on Lovecraft's 1936 novella The Shadow over Innsmouth, which is a part of the Cthulhu Mythos. [ citation needed ]

The creatures in the 2018 Netflix film Bird Box are strongly implied to be related to Cthulhu. [55]

Cthulhu appears in season four, episode seven of The Venture Bros., battling the Order of the Triad. [ citation needed ]

Cthulhu is mentioned in season two, episode 14 of Night Gallery, "Professor Peabody's Last Lecture". [ citation needed ]

Cthulhu appears in the climax of the film Underwater, worshipped by a civilization of underwater humanoids. [56]

Cthulhu, or at least his star-spawn, is set to appear in Lovecraft Country. [57]

Music Edit

Heavy metal band Metallica referenced Cthulhu in the song "Dream No More" from their 2016 album Hardwired. To Self-Destruct, [58] as well as on the 1984 album Ride the Lightning with the instrumental track "The Call of Ktulu", inspired by H. P. Lovecraft's novella The Shadow over Innsmouth, which was introduced to the rest of the band by Cliff Burton, [59] and on the 1986 album Master of Puppets with the song "The Thing That Should Not Be" (whose lyrics are inspired by The Shadow over Innsmouth and contain partial quotes from "The Call of Cthulhu"). [60]

The fifth studio album by Canadian electronic music producer deadmau5 features the song "Cthulhu Sleeps".

American metal band The Acacia Strain features a song titled "Cthulhu" on their album Continent.

The second album of British steampunk band The Men That Will Not Be Blamed for Nothing features the song "Margate Fhtagn". The song describes the band's meeting with Cthulhu while on holiday in Margate. [61]

English extreme metal band Cradle of Filth's fourth album, Midian, features a song titled "Cthulhu Dawn", [62] although the lyrics seem to have nothing to do with Lovecraft's sea-monster.

The songs "The Watchman" and "Last Exit for the Lost", by British gothic rock band Fields of the Nephilim, both reference Cthulhu (or Kthulhu as it is spelled on the album's inner sleeve). [63]

British progressive rock band CARAVAN released the song "C'Thlu Thlu" on the album For Girls Who Grow Plump in the Night (1973).

The penultimate track on the 2011 self-titled debut album by New Zealand sludge metal band Beastwars is titled "Cthulhu".

The album Stairway To Valhalla by Nanowar of Steel features a song titled "The Call of Cthulhu".

The song "Cthulhu" by German power metal and "SUPERHEROMETAL" band Grailknights mentions the city of Rlyeh.

The song "Angel of Disease" by American death metal band Morbid Angel references the Ancient Ones, Cthulhu, and Shub-Niggurath.

British synthwave band, Gunship, released the song "Cthulhu" in 2019, featuring a well-known quote from Lovecraft's The Call of Cthulhu and Other Dark Tales [64] narrated by horror-film director, Corin Hardy. [65]

Theater Edit

The story was adapted for the stage by Oregon-based theater company Puppeteers for Fears, who performed "The Call of Cthulhu" as Cthulhu: the Musical! a feature-length rock-and-roll musical comedy performed with puppets, with the Cthulhu puppet being the largest and most complex. The script and songs were written by playwright Josh Gross, [66] and after a successful run in Ashland, Oregon, the production toured the west coast in 2018, including a sold-out run at the Hollywood Fringe Festival. Of the show, The Portland Mercury wrote, "You haven't truly experienced Lovecraft's madness until you've experienced it in its truest form: As a puppet musical." [67]

The 2019 StarKid Productions horror-comedy musical Black Friday's main antagonist is an entity named Wiggly who takes the form of a plush toy that strongly resembles Cthulhu. The opening number "Wiggly Jingle" features the lyric "He's an underwater creature from outta this world", which is a direct reference to Cthulhu's origins. [68] In the second act, Wiggly is revealed to be a much larger cosmic entity who was using the plush toys and the hysteria they caused to destroy humanity. Wiggly's larger form is a loose-form puppet made out of the set dressing, but still has the recognizable Cthulhu shape. [69] The musical was written by Matt and Nick Lang with lyrics and music by Jeff Blim. Black Friday successfully ran at the Hudson Mainstage Theater in Los Angeles, California from October 31, 2019 to December 8, 2019.

Toy versions of Cthulhu have been released in support of games. A plush Cthulhu has become a kawaii cultural meme. [70]


What is a HDD?

The technology behind hard disk drives is well known and well tested. Hard disk drives have been around for more than 50 years, steadily increasing their storage capacity and decreasing their physical size. HDDs rely on spinning disks, or platters, to read and write data.

How hard drives work

Hard disk drives consist of one or more magnetically sensitive platters, an actuator arm with a read/write head on it for each platter, and a motor to spin the platters and move the arms. There is also an I/O controller and firmware that tells the hardware what to do and communicates with the rest of the system.

Each platter is organized into concentric circles called tracks. Tracks are divided into logical units called sectors. Each track and sector number results in a unique address that can be used to organize and locate data. Data is written to the nearest available area. There is an algorithm that processes the data before it’s written, allowing the firmware to detect and correct errors.

The platters spin at pre-set speeds (4200 rpm to 7200 rpm for consumer computers). Those speeds correlate to read/write rates. The higher the pre-set speed, the faster a hard drive will be able to read and write data.

Reading and writing

Each time you ask your computer to retrieve or update data, the I/O controller tells the actuator arm where that data is located, and the read/write head gathers the data by reading the presence or absence of a charge in each address. If the request was to update the data, the read/write head changes the charge on the affected track and sector.

The time it takes for the platter to spin and the actuator arm to find the correct track and sector is known as latency.

Drawbacks

The drawbacks to HDDs are a result of the mechanical parts used to read and write data, as physically finding and retrieving data takes more time than electronically finding and retrieving data. The mechanical parts can skip or even fail if they are handled roughly or dropped. This is a concern in laptops, but not as much in desktops. HDDs are also heavier and use more energy than comparable SSDs.

Benefits of a HDD

The benefits of a hard disk drivs are that they are a proven technology, and are frequently less expensive than a solid state drives for the same amount of storage. Currently, HDDs are also available with more storage space than SSDs.


EMMC VS SSD

You may read more information about HDD vs SDD or SD card vs SSD, but you only know a little about eMMC vs SSD. This article, however, mainly aims to talk about eMMC vs SSD to enhance your comprehension about them.

In consideration of the dominant importance of storage devices for laptops, it is important to distinguish these devices and choose the most suitable one.

Although both eMMC and SSD operate on the NAND principles, a great number of distinctions lie between the two storage devices.

The most dominant difference is that eMMC is a type of flash storage based on the MMC standard, while SSD is a type of solid-state storage.

Other detailed differences are listed as follows.

  1. eMMC and SSD enjoy different functions. eMMC is used as a temporary storage medium for a portable device while SSD is used as a permanent storage medium. You can choose one type of storage in accordance with your storage medium.
  2. eMMC and SSD enjoy different performance. The eMMC runs faster for small file storage and retrieval. However, the SSD delivers better performance in large file storage. The maximum data transfer rate of eMMC is about 400MB/s while the maximum transfer rate of SSD is much higher than that of eMMC.
  3. eMMC and SSD have a different number of NAND gates. Both eMMC and SSD operated on the NAND principles which allow data to run faster but eMMC typically has only one NAND gate while SSD tends to have more NAND gates. In this way, SSD is faster in reading and writing compared to eMMC.
  4. eMMC enjoys much less storage capacity than SSD. EMMC usually has storage space of 32 GB and 64 GB although the size of 128GB is available. As for SSD, it boasts much more space. 128GB, 256 GB, 320 GB and 512 GB are available.
  5. eMMC and SSD differ in connections. eMMC is often directly soldered onto the motherboard while SSD drives are usually connected to the motherboard via the SATA interface. If your laptop has no SATA interface, you are supposed to use eMMC.
  6. SSD and eMMC are made of different components. SSD is composed of powerful controller chips and fast NAND Flash memory, while eMMC is composed of similar components to an SD card or USB stick.
  7. eMMC and SSD are different in target consumers. eMMC is widely used in consumer-level electronics because its price is more affordable and acceptable. SSD is rarely used in consumer-level electronics because consumers can find another more cost-effective alternative.

As what has been mentioned above, however, bears some deficits as well. For example, it is less cost-effective than other types of storage and possesses less space compared with HDD. But it is certain that SSD has better performance compared with other storage devices.

Thus, you may wonder when you need to replace eMMC with SSD. In order to know more, just go on your reading.

To get better performance, a good way is to replace laptop hard drive with SSD. This post shows how to replace a hard drive without reinstalling Windows.


Degaussing

Degaussing is a process of exposing the magnetic media to a strong magnetic field of a degausser to disrupt the recorded magnetic domain. This method is relatively efficient in purging diskettes, damaged or inoperative media, and media with large storage capacity. And it also makes data unrecoverable even in laboratory environment.

However, degaussing work of modern high-density disk is more difficult than that of older disks like magnetic tape and floppy disk. Modern high-density disk degaussing requires higher magnetic field, in other words, more bulk and expensive degauss equipment, which also means higher cost.

In addition, although degaussing will not cause damage to media, it will also make the media lose economic value and unusable.


Why Does a Herniated Disk Happen & Will It Go Away?

Anybody who has ever experienced a herniated disk before knows how painful it can be. Movement can make it worse and the frustration of waiting for it to heal is enough to make you go crazy.

Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy

One minute you’re completely fine, bending down to pick something up. The next minute a shooting, irritating pain is plaguing your neck or back.

You think it might be a herniated disk, but what exactly does that mean? Spine surgeon Dominic Pelle, MD, explains what’s happening to your spine.

What is a herniated disk?

One of the simplest ways to understand a herniated disk is to think about a jelly donut. (Yes we know it’s weird, but bear with us.)

You have 24 disks in your spine – ranging from the very top (called the cervical spine) down to the lower spin (called the lumbar spine).

The disks all the way up and down your spine act as shock absorbers to your movement. The disks help hold your spine up and allows it to bend and move.

“If you have a herniated disk, think about it as a jelly donut,” explains Dr. Pelle. “The outside of the disk is like the dough of the donut and is called the annulus fibrosis. The inside of the disk is the jelly in the donut, which is called the nucleus pulposus.”

Now imagine that the donut has a hole somewhere in it and you press down. The jelly is going to squirt out of it – just like the nucleus pulposus would from your actual disk in your spine.

When the nucleus pulposus pushes outside of the annulus fibrosis and touches a nerve, that’s when you experience the pain from a herniated disk.

Causes of a herniated disk

Movement, injury, pressure, age or just plain bad luck can cause the nucleus pulposus to push through the annulus fibrosis – just like the inside of a jelly donut would if you pressed down on it.

“Some people get in an accident and have a herniated disk afterwards, other times it’s something as simple as bending down to tie a shoe when it happened,” says Dr. Pelle. “Most often people will know exactly when it happened or what caused it because the pain usually happens right away.”

A herniated disk could also be caused by disk degeneration, genetics or a combination. Certain activities like lifting weights or playing a sport might also cause a herniation.

What does a herniated disk feel like?

People experience symptoms of a disk herniation when it presses on a nerve or the spinal cord. A pinched nerve is called radiculopathy and typically causes shooting pain, numbness or weakness. Depending on what nerve is pinched, it can cause pain in a variety of places.

If you have a herniated disk in your lumbar spine, the pain might come down your leg, down your butt, over the hip and down the leg, says Dr. Pelle.

If your herniated disk is pinching a nerve in your cervical spine, it might cause arm pain or weakness that shoots down your shoulder or upper back.

It all depends on the level of the herniated disk and what nerve is getting pinched.

“Pressure on your spinal cord is a bit more serious when you start to have symptoms from it,” explains Dr. Pelle. “That’s usually called myelopathy and has to do with loss of sensation or control in certain areas of the body.”

How long does it take for a herniated disk to heal?

The average amount of time it takes for a herniated disk to heal is four to six weeks, but it can get better within a few days depending on how severe the herniation was and where it occurred.

The biggest factor in healing a herniated disk is time, because most often it will resolve on its own.

Healing time also depends on what recovery looks like for you and what type of treatment you try.

Treatment for a herniated disk

Dr. Pelle says there are some treatment options that can be started right:

  • Ice and rest. and stretches.
  • Medication (anti-inflammatory medicine or muscle relaxers can help the nerve calm down).
  • A dose pack of steroids.

Surgery is an option for some people who fit the criteria for it.

“I always tell people that there are three prerequisites for surgery,” says Dr. Pelle. “You have to have had the pain for at least six weeks. You have to fit the requirements from the physical examination and medical history. And we need to have a serious conversation about how bad the pain is bothering you and affecting your quality of life.”

Surgery on the spine is serious and should be weighed accordingly.

If you think you’re dealing with a severe herniated disk or the pain just won’t go away, schedule an appointment with your doctor.

Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy


Conclusion:

Based on the testing we can conclude that there is no significant difference in performance for sequential workloads between the different types of virtual disks. Most common IO workloads on all flash arrays will not be impacted by the type of underlying disk used as seen in the low latencies below 5ms for all workloads.

Some of the disadvantages of using Eager Zeroed thick disks are avoided by using All Flash arrays:

  1. Time to provision on all flash arrays like PURE, by leveraging VAAI for disk creation is very quick and done in a few minutes even for large datastores.
  2. Storage Utilization inefficiency is avoided as the amount of actual storage consumed is optimized for both thin and thick disks by the inbuilt compression capabilities of the storage platform.

For High IO workloads, we can conclude that using eager zeroed thick disks would provide the best performance even in all flash arrays for all types of write workloads. If the storage array has built in efficiencies to compress and store only unique data and is VAAI compliant, most of the disadvantages of eager zeroed provisioning are avoided.

Mohan Potheri

Mohan Potheri is VCDX#98 and has more than 20 years in IT infrastructure, with in depth experience on VMware virtualization. He currently focuses on educating customers and partners of "AI/ML"&hellip