Talk:RAID

Fake RAID: hardware or software?

I think this edit is incorrect, because the paragraph starting with Since these controllers use proprietary disk layouts... refers to the one that precedes it, Because these controllers often try to give the impression of being hardware RAID controllers.... I think the real error is that those two paragraphs should go at the end of the Hardware-based section, not the Software-based section. --Fstanchina (talk) 16:41, 27 January 2008 (UTC)

I don't think so, because the controllers that "use proprietary disk layouts..." are hardware, while software RAID is the one that tries "to give the impression of being hardware RAID...".
-Garrett W. (Talk / Contribs / PM) 03:35, 22 November 2009 (UTC)

Issues with RAID

Concerning Atomicity: Are those issues also resolved with simple data journaling, or is that not enough? Esspecially are they resolved by Reiser and by ext3 with full journaling?

Concerning Unrecoverable data: Most drives remap bad sectors on write, don't they? So, if a sector is unreadable on one disk, but there is enough redundancy, the controller could simply _write_ the reconstructed sector to the disk, and it's the same as if it would use an own remapping table, wouldn't it?

--JensMueller (talk) 01:01, 10 February 2008 (UTC)

RAID5 algorithm

somewhere I found this one:

( (Drive 1) XOR (Drive 2) ) XOR (Drive 3) = (Drive 4)

I do not get this: why 3d+1p?

I think is better 2d+1p in a single xor operation

actually I thought raid5 algo was like this:

1d' 1d" 1p 2d'

2p 2d" 3p 3d'

3d" 4d' 4d" 4p

5d' 5p 5d" 6p

6d' 6d" .. ..

.. .. .. ..

...only a single xor computed on d' d" pair.

this is k complex algo, instead the above one is more and more complex (and slower) for bigger arrays.

ok, xor is fast... but N*xor is slower than only one. —Preceding unsigned comment added by 159.149.147.21 (talk) 15:35, 7 September 2009 (UTC)

Beyond RAID6

RAID5 has single parity, RAID6 has dual parity.

I'm sure there are error correcting codes that can go beyond that.

What issues would occur with e.g. a (hypothetical) 6+3 RAID 6+? Are there experimental implementations of such stuff? --JensMueller (talk) 01:08, 10 February 2008 (UTC)

Well, both of those use parity. RAID 2 uses a Hamming code which I would consider "beyond" simple parity. What exactly do you mean by "beyond"? Cburnett (talk) 03:40, 10 February 2008 (UTC)

triple parity, i.e. that three devices can fail without using data. --JensMueller (talk) 09:55, 10 February 2008 (UTC)

Oh, I just saw that this is addressed in Standard RAID levels ... --85.180.64.175 (talk) 00:05, 23 March 2008 (UTC)

Semi-protected

I have semi-protected the page because of CONSTANT change from "Inexpensive" to "Independent". The original article by Patterson, Gibson, & Katz is titled "A Case for Redundant Arrays of Inexpensive Disks (RAID)". They coined the term and that's what it should remain unless someone comes up with a really compelling reason to override those who coined it.

If anyone has an idea how to avoid this constant change so semi-protection can be removed then I'm all ears! Cburnett (talk) 21:23, 22 February 2008 (UTC)

The problem is that we need a reliable source to indicate its current meaning. Just because it meant something in the 1980s, does not mean that it still means the same thing.

However, if no such source shows up, why not keep "inexpensive" and make a note (later, under "Meaning of Acronym", for example) to the effect that ""Inexpensive" is sometimes replaced with "Independent", but the former term is the one that was used when the term "RAID" was first coined by at Berkeley"--Ernstk (talk) 16:51, 1 March 2008 (UTC)

Second sentence: RAID is also sometimes referred to as "Redundant Arrays of Inexpensive Drives" or "Redundant Arrays of Independent Disks/Drives". That doesn't stop drive-by changing of Inexpensive to Independent. Cburnett (talk) 17:02, 1 March 2008 (UTC)

Can't the introductory sentence simply be replaced with the following?

"RAID (Redundant Array of Independent Disks or Redundant Array of Inexpensive Disks) is......."

This includes both terms immediately so any argument over the correct one is quashed. The terms also appear in alphabetical order, if anyone should argue over which appears first (!) Both terms were used recently in the final of the respected British quiz show University Challenge - if they couldn't decide on a correct answer, no-one can! --- Soulhunter123 (talk) 21:24, 2 March 2008 (UTC)

That is one solution, yes. Though I could pose the argument that Inexpensive should appear first since it was the first used term (chronological over alphabetical since alphabetical is wholly arbitrary and dumb-luck in ordering).

The whole thing is an interesting deal. The authors used "Redundant Array of Inexpensive Disks" and first introduce the acronym RAID in section 6 as "our acronym...is RAID." Since then the acronym has been accepted over Redundant Array of Inexpensive Disks and then changed to mean something different (probably out of confusion). That considered, I reject that Inexpensive and Independent are equal in terms of how you propose they should be presented.

I'd propose not defining RAID and leaving that to the first section on History but I guarantee...GUARANTEE...someone will add it to the introductory sentence. The problem is people changing without bothering to read. The rest of the introductory sentence starts with "as named by the inventors" which Independent is not what they named it. So rationally explaining terms won't work either because people aren't thinking before they change it. Cburnett (talk) 22:01, 2 March 2008 (UTC)

The disambiguation page for "Raid" reads "Redundant Array of Independent/Inexpensive Disks", and has done for over a year. Can't this just go in the opening sentence, and let's be done with it? The second sentence can simply read "Originally dubbed Inexpensive Disks by the creators, the different naming convention (Independent) has since arisen within the industry." And finally, I'm totally impartial to the subject of RAID, but I think chronological order is silly for a neutral, encyclopedic point of view. Alphabetic is the way to go. --- Soulhunter123 (talk) 01:02, 3 March 2008 (UTC)

Please don't bastardize the meaning of "neutral" as it means in WP:NPOV. Cburnett (talk) 01:09, 5 March 2008 (UTC)

I have edited the introduction to encompass both names, entirely seperately, in chronological order (due to the added descriptions in parenthesis). Hopefully this will put an end to the whole issue. Personally, I still think the article is messy, particularly the introduction which drones on for about three paragraphs longer than it could be. If you could unprotect the page now, that would be great. --- Soulhunter123 (talk) 17:17, 7 March 2008 (UTC)

Agreed--Kelvin_HO^{Wiknerd(talk)} 07:40, 29 March 2008 (UTC)

Do we have a cite for "Independant"? Bulbous (talk) 14:36, 29 March 2008 (UTC)

There seems to be a (trivial) error in the semi-protected section "RAID — which stands for Redundant Array of Inexpensive Disks (as named by the inventor[1])" Reference 1 seems to show 3 inventors, not 1, so that should read "...by the inventors[1]" —Preceding unsigned comment added by 212.84.126.120 (talk • contribs) 13:10, 23 September 2008 (UTC)

Done. Note that the page is no longer protected, so you are welcome to make such changes yourself in the future. --Zvika (talk) 17:32, 23 September 2008 (UTC)

Umm, if all of the disks are required in order for a RAID system to work at full capacity, then the disks are not independent. Additionally, all disks in a RAID system are working in tandem, NOT independently. Aditionally, the technology of RAID was introduced to combat the necessity of the SLED (Single Large Expensive Disk) so please change it back to Inexpensive. —Preceding unsigned comment added by 98.210.97.186 (talk) 00:13, 12 January 2009 (UTC)

It's perhaps a semantic argument, but the disks can be seen as being accessed independently, at least by the controller itself. Actually reading from a Volume on those disks in the OS requires more more than one disk, but unless someone actually proposing to changing the name to Redundant Array of Interdependent Disks, I don't think it much matters either way. I'd like to re-write the blurb on the marketing reason for changing the name to at least include the obvious, which is that often, the disks are not inexpensive, it was simply the original intention. Ar-wiki (talk) 16:23, 9 February 2009 (UTC)

rewrite so that dumb people can understand it?

this article is a little bit hard for non-technical people to understand. 132.161.187.38 (talk) 13:14, 13 March 2008 (UTC)

I quite agree, and I have re-written/re-structured the introduction and first section to better explain RAID in a more simplistic, readable manner. Hope this helps you and others! --- Soulhunter123 (talk) 04:27, 14 March 2008 (UTC)

Dumb people rewrite - Purpose and basics

I agree that the article lacked a simple explanation (not for dumb people, but for people who didn't know it all beforehand), and added a new "Purpose and basics" section. It's been extensively edited. I didn't entirely agree with the edit, and was trying to improve the new version, but came to the conclusion that it was basically less clear and simple than my original; I'd like others, particularly the non-technical, to consider the versions and decide what text to use. For now I've reinstated my version, extensively revised, for consideration, and would suggest that neither Soulhunter123 nor I touch the section for a while.

Basically, this section should be simple but never simplistic, and should convey:

• RAID looks to you just like one disk.
• Different RAIDs give you a combination of faster performance and data safety against disk failure.
• RAID 0 uses at least 2 disks and is faster but unsafe (I originally said 2 disks, unduly restrictive)
• RAID 1 uses 2 disks, protects data, and loses 50% of capacity
• RAID 5 uses any number of disks, protects data, and gives more capacity that RAID 1.
• It is possible to protect data against more than one disk failing; read the article for details.

In fact, maybe the whole section should be replaced by just the above? It's actually undesirable to give too much detail and consider all possibilities (mirroring more than 2 disks); after all, it's followed by a whopping great discussion of just about everything. This section must be simple, but I do think it should avoid being simplistic.

Details I wasn't happy about:

'extra "summary" data' seems confusing

"is written alongside the main data on a disk" it's distributed over the array, not on the same disk as the data in question - this is confusing

"data on it is reconstructed from the summary data on the other disks" it's reconstructed from the remaining good data, corrected with the redundant data. I think I made the same implication

"[redundant RAIDs] requiring, on average, roughly half the size of the main data" no

"For increased performance, there are various combinations of configurations" I think for the user unfamiliar with RAID, RAID 0 is enough. The full article details the others.

"lost or corrupted" for all practical purposes, lost. Data which is corrupted but not lost makes you think of perhaps a document with a bad paragraph

"Another approach, 'RAID 1', stores the same data on each disk in the array so that the failure of one disk causes no loss. This configuration allows the user to consume only half the total capacity of the array's disks." In practice, it's very rare to mirror more than 2 discs. And if we do, we can lose all disks except one, and we lose the capacity of all disks except one.

I'm sure what I wrote can be dissected in this way, and improved in the process.

Best wishes, Pol098 (talk) 17:07, 14 March 2008 (UTC)

The vote of a "Techy" on this subject may not be worth much but I feel this section makes the content more confusing instead of less. It is my opinion that this section adds nothing unique to the article as a whole and much of what it does describe is done out of any logical order. As a result I would suggest this section be removed from the article entirely. The very next section is mostly a repeat of this anyway. Furthermore I would suggest that RAID levels not be referenced until after the section on RAID levels, as knowing the any part of how one paticular set-up works in not integral to the understanding of the basic idea. Neverlucky 13 (talk) 22:34, 27 January 2009 (UTC)

History

I've removed Sixth and Tenth from the section about the original paper because they weren't discussed in the original paper. They are discussed elsewhere in this article. There are still a few internal inconsistencies in this article. Richard Manion 13:50, 22 April 2008 (UTC)

Reliability terms unclear

Failure rate "The mean time to failure (MTTF) or the mean time between failure (MTBF) of a given RAID is the same as those of its constituent hard drives, regardless of what type of RAID is employed." This does not clarify whether this is the "sticker" MTTF on the drives, or a number calculated from the average or lowest of these drives. Failure rate is not a synonym for MTBF, though they are related. Possibly both should be defined and linked to the appropriate articles. —Preceding unsigned comment added by 124.171.192.218 (talk) 13:23, 26 May 2008 (UTC)

RAID Principles

A mention somewhere of information theory is possibly appropriate, given that RAID is a communications system where you're essentially sending data to yourself, and the channel is the RAID array. I'm pretty sure RAID codes are close to other communications codes, also. —Preceding unsigned comment added by 124.171.192.218 (talk) 13:23, 26 May 2008 (UTC)

Two partitions to emulate Raid 1E

I added a fact tag to the suggestion an administrator could make two partitions and then mirror across disks and stripe between partitions as I think it needs to be attributed to a reliable secondary source making that suggestion. It seems a rather odd suggestion to me as it would be particularly punitive on the writes since you can't sequential write (with 1E I presume the mirrored strip [1] is written sequentially). Perhaps this config is useful in some cases, I've never set up a server or RAID array and I guess if all you care about is read it should be fine. Also the sentence needs to be improved if it's kept. As I understand it, to emulate a Raid 1E config, if you have drive A B C with each having partition 1 & 2 you need to do something like have A1 and B1; C1 & A2; B2 & C2 as a set of mirrors. You then stripe across these 3 mirrors. Alternatively, you need to make 2 stripe arrays each containing 1 partition from each disk and then you mirror across these stripes but you need to make sure the mirror isn't on the same drive. I guess if it's possible to specify the order of disks in the strip array (so for example stripe array 1 writes to disk A then B then C while strip array 2 writes to disk B then C then A) then it should be fine. The sentence doesn't really convey that, at least to me. Indeed I thought it was suggesting you mirror across each 3 disks and then stripe between partitions on a disk which gives you a non-sequential mirror array with the capacity of 1 disk. Nil Einne (talk) 13:12, 7 October 2008 (UTC)

Wow that's confusing. I don't have a clue as to exactly what you're trying to describe.
-Garrett W. (Talk / Contribs / PM) 03:35, 22 November 2009 (UTC)

Strategy comparison for RAID implementations

The aforementioned 1E is getting down to the "partition level" and seems to be more likely in a software-implemented RAID strategy, but if there is a reference that could be cited for the fact tag purposes for either hardware, or any implementation of this, I suppose that would clarify the idea. Also, there is a merge / new article proposal for a section from Vinum volume manager at the moment. --Kuzetsa (talk) 20:55, 1 November 2008 (UTC)

RAID 50 not mentioned?

I note that RAID 50 (5+0) is not explained in this article, surely it is common enough to do so? I have personally not come across RAID 53 before now! I do not feel qualified to make the changes, in general I congratulate the article. 79.65.152.127 (talk) 20:25, 26 January 2009 (UTC)QuagSwag

Space efficiency

What is the source for the space efficiency figures in the article. They don't seem to be the theoretical maximums. Plugwash (talk) 22:58, 26 January 2009 (UTC)

Shouldn't RAID 1 space efficiency be n/2 ? —Preceding unsigned comment added by 66.162.146.82 (talk) 16:56, 19 February 2009 (UTC)

RAID 3 Error Correction

In the section Standard Levels, the part on RAID 3 is misleading or incorrect. While the article currently states that RAID 3 can withstand a failure in the parity drive, in actuality it can both detect and correct errors in the case of disk failure of any drive. Structured Computer Organization 5th Ed. by A. Tanenbaum (note: this is my first attempt at a contribution to a wiki please excuse any deviations from standard practices) states, in a section on RAID that

     "At first thought, it might appear that single parity bit gives only error detection, not error correction.  For the case
   of random undetected errors, this observation is true.  However, for the case of a drive crashing, it provides full 
   1-bit error correction since the position of the bad bit is known. If a drive crashes, the controller just pretends that
   all its bits are 0s.  If a word has a parity error, the bit from the dead drive must have been a 1, so it is corrected."

So while the error in the article is technically small I feel it overlooks a rather large feature of this RAID level. 138.87.154.174 (talk) 19:15, 27 January 2009 (UTC)

Discussion of Write Penalties associated with parity-based forms of RAID

I was really surprised to see there's no information on the various write penalties associated with RAID-5 and RAID-6.

Has there been a previous discussion on this and perhaps there were reasons for excluding the topic? 71.82.143.70 (talk) 18:48, 29 January 2009 (UTC)

Not just RAID-5 and RAID-6, or even all parity based forms of RAID. RAID-1 has a write penalty as well, and it's not parity based. —Preceding unsigned comment added by 128.222.37.20 (talk) 12:36, 20 March 2009 (UTC)

Remove 'backup' in Purpose and Basics?

In the Purpose and Basics section, it says that RAID 1 "could be described as a real-time backup solution." I would recommend changing it to read "RAID 1 (mirrored settings/disks) provides redundancy for saved data" or something like that. RAID 1 is not a backup because you can't revert to a previous version of a file and can't recover deleted data any easier than you could with a single disk. If data is corrupted from bad blocks on a single drive, chances are good that it can be recovered/rebuilt from the mirror (good drive), but again, that's redundancy, not backup. Werikblack (talk) 16:22, 18 March 2009 (UTC)

I agree. I'd probably go with something along the lines of "RAID 1 (mirrored settings/disks) provides redundancy for existing data in situations where up to n-1 disks can fail without loss of data" or something along those lines. I have seen some text books list RAID 1 as a "backup solution", but agreed - I don't think it should be written to seem like a backup solution.

Legios (talk) 02:11, 19 March 2009 (UTC)

I've had a stab at rewriting it. Hopefully it sounds a bit less.. backup-y.

Legios (talk) 01:05, 20 March 2009 (UTC)

Looks great! Thanks for the edit! I like the images too.

Werikblack (talk) 05:01, 1 April 2009 (UTC)

Agree Fault tolerance is certainly not the same as backup. Consider the case of a malware infection: with RAID-1, both drives would be equally infected, and neither would provide an uninfected copy to restore.
-Garrett W. (Talk / Contribs / PM) 03:35, 22 November 2009 (UTC)

Performance impacts of software RAID

From the article: "With traditional "real" RAID hardware, a separate controller does this computation. In other cases the operating system or simpler and less expensive controllers require the host computer's processor to do the computing, which reduces the computer's performance on processor-intensive tasks."

I feel that this needs some qualification. "reduces the computer's performance on processor-intensive tasks" should read "reduces the computer's performance on tasks that are both processor- and disk-intensive" -- if the RAID isn't in use, it doesn't affect performance at all. Also, for the most part reads and writes to the software RAID are I/O bound, even under RAID-5. Modern CPU's can perform the RAID computations fast enough that they are always waiting for the disk to catch up, so the real difference in performance between hardware and software RAID is often negligible.

I don't know enough about CPU pipelining to say this authoritatively, but I also think it's likely that the non-I/O computations of a given task (that is, the ones that would be slowed down by the CPU having to do software RAID computations as well) can often be run in parallel with the RAID stuff, so they're not waiting on the CPU. (If those tasks *do* need CPU registers or components that are being used for RAID computation, odds are it's because they wanted a disk access, and if that's the case the task is I/O bound anyway, not CPU bound.)

In addition to all of that, multi-core processors would just offload RAID stuff to a different core. This would have zero performance impact on applications unless they were well designed to take advantage of multiple cores (which most applications are not), and are performing tasks that are parallelizable (many tasks are not).

199.60.222.226 (talk) 22:39, 26 March 2009 (UTC)

RAID 5 not good enough

I've noticed a growing sentiment against RAID 5 among administrators of large data centers. There was a great talk "Trends from the Trenches" at the Harvard Biomedical HPC Summit last year, which detailed the problems of RAID 5 masking serious errors until catastrophic loss occurred. They recommend RAID 6 now, and they reject any storage/controller products that are not proactive about disk scrubbing and consistency checking. See: http://blog.bioteam.net/ 24.16.88.14 (talk) 20:02, 31 March 2009 (UTC)

FreeBSD loader

I'm reverting the addition of "the" from the reference to loader for FreeBSD within the "Operating system based ("software RAID")" section. 'loader' is actually the name of the program

Taken from the manpage at http://www.freebsd.org/cgi/man.cgi?query=loader&apropos=0&sektion=8&manpath=FreeBSD+7.1-RELEASE&format=html:

The program called loader is the final stage of FreeBSD's kernel boot- strapping process.

Legios (talk) 06:48, 9 April 2009 (UTC)

RAID bug killer

what does any of this have to do with the bug spray? shouldn't there be a disambiguation? 71.112.216.106 (talk) 19:43, 5 June 2009 (UTC)

There is a disambiguation page: Raid
-Garrett W. (Talk / Contribs / PM) 03:41, 6 June 2009 (UTC)

That is interesting because if you google search for Raid the first result is the Wikipedia page RAID which is identical to the Raid except for capitalization. This seems quite confusing but thanks. 71.112.216.106 (talk) 06:01, 6 June 2009 (UTC)

Google doesn't make a difference between capitalized and normal letters. Rchard2scout (talk) 18:07, 4 September 2009 (UTC)

Striping versus mirroring

I came here to learn, among other things, what these terms mean. I go away uneducated. Mirroring is defined in the introduction, but striping is not defined but just "used." Please add a definition for the term "striping". —Preceding unsigned comment added by 71.70.224.93 (talk) 18:59, 4 July 2009 (UTC)

OS X Server raid 5

The source referred to in the page [7] is dead, this is the new page: [2] BUT it has no mention of raid 5 anymore, so I think it's canceled for snow leopard server. —Preceding unsigned comment added by 195.13.11.226 (talk) 11:58, 7 July 2009 (UTC)

"Hot spare"

In the section "How parity is calculated" is the phrase, "replacement ("hot spare") drive". I do not believe "hot" is germane to the subject. "Hot" refers to the fact that the computer does not need to be powered down for drive replacement. It has little to do with the fact that the RAID array can rebuild a failed drive onto a new drive. 207.124.15.65 (talk) 13:17, 29 September 2009 (UTC)

Vertical striping

We should mention somewhere vertical striping ... I'll add more to this later, but just a reminder! —Preceding unsigned comment added by Fishsponge (talk • contribs) 16:04, 23 October 2009 (UTC)

Uncited claim

The paragraph beginning with "RAID is not a good alternative to backing up data" needs citing for this claim. Also, the term "unsafe" sounds like an opinion. All of Section 3 is uncited. --jacobmlee 10:13, 28 Oct 2009 CDT

Duplicated content in Organization and Standard Levels

The same information is present in both sections. I don't see a way to quickly combine them, so I'll just mark my concern and hopefully someone working more intensively on this article can consider it. It seems that both sections were done independently. The article doesn't read as an organized whole. —Długosz (talk) 17:23, 4 November 2009 (UTC)

Raid10 and minimum drive requirement

The definition of Raid10 provided on this wiki page states it is possible to implement with 2 drives. However the external links at the bottom of the page only show support for a 4 drive implementation as the minimum. Can you clarify how it is possible to implement Raid10 with just two drives? Thanks. Rjdevine (talk) 17:19, 20 November 2009 (UTC)

I am also not aware of RAID 1+0 being possible with 2 disks. If no one shows how this is possible within a reasonable amount of time, I'll probably just take that bit out of the article.
-Garrett W. (Talk / Contribs / PM) 03:35, 22 November 2009 (UTC)

Needs a more practical "configuring SATA RAID" section

The overwhelming majority of people looking at this article are trying to figure out what are the implications of lines like this in the spec for a new mainboard:

• SATA 6Gb RAID 0
• SATA 3Gb RAID 0, 1, 5, 10

That is exactly the specification you will see presently from Gigabyte describing the capabilities of their P55- and also X58 (Intel LGA1156) and 790FX (AMD AM3) mainboards. It's also exactly what you can expect to see in the first generation from ASUS, ASRock, MSI, Eclipse, and so on. So what this means is that the people who are choosing whether to buy this part or not, or what it might be able to do with their new/expensive SATA6Gb SSD discs and their legacy SATA3Gb discs, really need simple coverage of the tradeoffs in using two SATA6Gb in a RAID 0 (the mainboards at present only support two SATA6G connections, that's a limitation of the Marvell SE9128 controller that these boards will be using probably until 2011/2012 when this capability goes in the main chipset.

Obviously (to anyone who understands RAID), it's the OS and applications and at most a few settings files that should be on the RAID0 array which is an 800 mile an hour gokart.

User data should be on something like a SATA3 RAID5 or (if you must) RAID1 or RAID 10 or just kept on USB3 drives (all the SATA6G motherboards support 4.8Gbps USB3 as well) or (best) a file sharing router with only a local cache of data on the scary RAID0.

So the most common configuration problem is going to be setting up two SATA6G drives in a RAID0 for OS and applications and two or more SATA3G or USB3 drives in a RAID 1/10/5. Factors like how identical the drives must really be (identical models with same number of platters and so on, or just nearly identical capacities?), whether you can really do it with two and if so with what controllers, whether RAID 5 is advisable at all (see the point above about major data centers moving to RAID6 exclusively), all should be covered.

But as for the use of RAID and SATA6G, there really is no other sensible configuration (you aren't using SATA6G for reliability you're using it for speed, and you can't set up a RAID 5 or even a RAID 10 or RAID 1 with current motherboards) for the next year or so on current desktop PC technology, so this should be fully explained.

It would take no more than a paragraph to explain this and would save a lot of data. ;-D —Preceding unsigned comment added by 142.177.109.5 (talk) 17:28, 4 December 2009 (UTC)

RAID0 vs. faster bus

Another issue worth exploring in this article is whether RAID0 performance is worth the risk or whether simply moving up to a faster bus speed with a single disk is a better choice. With USB3 getting about 5.5x the burst speed of USB2 in high end systems of the type that might go SATA3G or SATA6G RAID0 instead, it's legitimate to ask whether the complexity and risk of RAID0 configuration is worth it at all. It may have been a stopgap, like earlier IDE and ATA RAID systems were, until faster and wider buses came along. At 4.8Gbps (USB3) and 6Gbps (SATA6G) the PCIe channels are saturated anyway and one starts to interfere (marginally) with graphics performance on a typical desktop PC because of use of multiple channels. One doubts if any RAID0 configuration is going to speed up disk access by 5.5x or even double.

So maybe there needs to be a big caveat that unless you have two drives doing nothing of any great value that are identical or nearly so, a RAID0 slaving them together to run an OS and applications may actually be outperformed by one new hard drive on USB3 or SATA6G.