Talk:RAID

Reference websites and other stuff

Hello, A876! Regarding your edit comment, there are three things:

• Nobody owns anything, as you've described it for some reason; what I've done is called peer review and articles actually benefit from it. Moreover, it would be great if many more articles had active peer reviewers.
• Article-level consistency should be more important than using all of the possible variants, and almost all references in this article have domains or hostnames for the values of their |website= parameters (where applicable, of course).
• Wording can always be better, and small mistakes or typos should be discussed or corrected in a friendly manner instead of beind called "cruft" that's "proudly" put into an article. If there's anything causing a disagreement, we're here to discuss it.

With all that in mind, I've restored the references and improved the wording a bit further. Hope you agree. — Dsimic (talk | contribs) 22:30, 20 April 2015 (UTC)

Any chance of mentioning the 'old' name for RAID; which was "Redundant Array of Inexpensive Disks"? 203.214.22.116 (talk) 01:13, 14 March 2017 (UTC) Oops! I just found it... Sorry. 01:15, 14 March 2017 (UTC)

Comparisons of RAID 5 and other RAID levels are incorrect.

In the summary of RAID 4, it is contrasted with RAID 2 and 3. A quote "As a result, more I/O operations can be executed in parallel, improving the performance of small transfers.[2]" This is only true for reads. It is untrue for writes. RAID 4 serializes writes and can perform only 1 at a time. This is because all writes, by definition, must update their respective parity data and in RAID 4 this parity resides on a single spindle. RAID 4 does one write at a time, whether small write or full stripe, exactly like RAID 2 and 3. Worse it does so without their bandwidth advantages.

Further the reference to NetApp's RAID-DP is misleading. It's not RAID-4. Its closer to RAID 6 since each stripe has two parity blocks and one is diagonally formed.

Next, the key advantage of RAID 5 is that its parity is distributed over all the members of the raid string. Unlike RAID 4, a write is not serialized by a single spindle. On a RAID 5 array the number of simultaneous writes can be as a high as 1/3 of the number of members in the string, e.g. a 15 drive string could have 5 simultaneous writes occurring. A RAID 4 string can never have more than 1 regardless of its size. The article leads you to believe RAID 4 has some advantage, when it's all the other way.

Lastly, all of the negative points you make about RAID 5 are true for RAIDs 1, 3, and 4 as well. A read failure during rebuild or degraded operation (one drive failed) can happen for any of them and would be equally unrecoverable. You don't point any of that out.

The comments on RAID 5 have a 'sky is falling' tone and lack the above perspectives. — Preceding unsigned comment added by 73.16.141.73 (talk) 00:29, 7 December 2015 (UTC)

Could add something about assumptions: who is expected to benefit from this? No mention of Windows 7 Pro. User trying to do mirroring (RAID 1) having come across it in the create and format hard disk partitions section of control panel. Well the "system crash" section in this Wiki may be a warning to the newcomer, but Dsimic has labelled my point about power interruption as pretty much a nonsense. Is Dsimic suggesting the assumption that a UPS is what everyone would already have before thinking about RAID? Where would they have come across that knowledge? On a non-mirrored system a power failure is overcome easily at the next boot. It does not require a message sent to Microsoft &c, the way a "crash" may. Soundhill (talk) 12:00, 19 January 2016 (UTC) Soundhill

RAID 1 offers no parity

The article states RAID 1 offers no parity, but a mirror is an even parity. I think it adds no value to explain this to the reader, but maybe it can be corrected? — Preceding unsigned comment added by 145.53.72.151 (talk) 18:54, 19 January 2016 (UTC)

RAID 1 needs more

The article says:

> The array will continue to operate so long as at least one member drive is operational.

There is no description of the failure scenario.

For people that are new to RAID, we could use a more complete description of what happens when a drive fails in RAID 1. For instance, is there a light or alarm, etc? Just another line or two would complete the description. Consider that a RAID 1 enclosure for two drives is the least expensive and most marketed RAID enclosure, so the Wikipedia description of RAID 1 is going to bring a lot of views. Thanks 75.110.98.103 (talk) 23:38, 4 February 2016 (UTC)

Well, any additional description would be highly system-dependent and confusing at least. For example, many people use software-based RAID, as a functionality provided by the operating system, so there's no fancy warning light in case of a drive failure. — Dsimic (talk | contribs) 10:19, 5 February 2016 (UTC)