blafarm

Low-Power Enterprise Drive Recommendations for Linux Software RAID5

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I need to build several 4-Drive Linux-based servers that will be running software RAID5 using 2TB drives.

My enclosures are small form factor Shuttle Computers -- so I'm looking for very low power-consumption and very low heat-generation.

Drive reliability is of utmost importance -- and as much as I'd like to save money -- I simply can't do it at the cost of a higher data loss probability.

I like the concept of the Caviar Green products -- but the manufacturer warns -- and users report -- a myriad of problems with RAID configurations.

That product led me researching the WD RE4-GP -- but I can't find decent reliability reports on that drive.

Are there any highly-rated, low-power, low-heat, enterprise-level drives suitable for software RAID5 deployments that I should be seriously considering for this application?

I should probably also mention that these RAID units might need to operate in ambient temperatures reaching 100 degrees F.

Thanks very much in advance for any and all advice.

Edited by blafarm

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Someone else would have to confirm, but in that environment I think you'll find more tolerance for the consumer green drives from WD and others.

As to the RE-4 GP, we've worked with the regular RE4, it's a very nice drive, fast and reliable. The GP version is probably just as good as it's their enterprise product. I don't think I could justify the price though over your typical $99 2TB green.

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Someone else would have to confirm, but in that environment I think you'll find more tolerance for the consumer green drives from WD and others.

As to the RE-4 GP, we've worked with the regular RE4, it's a very nice drive, fast and reliable. The GP version is probably just as good as it's their enterprise product. I don't think I could justify the price though over your typical $99 2TB green.

Thanks very much for your reply Brian.

I'd rather not pay the premium either -- but when the manufacturer clearly states at the bottom of their "Green" product page that:

"WD Caviar Green Hard Drives are not recommended for and are not warranted for use in RAID environments..."

"Please consider WD's Enterprise Hard Drives that are specifically designed with RAID-specific, time-limited error recovery (TLER..."

"[which] are tested extensively in 24x7 RAID applications, and include features like enhanced RAFF technology and thermal extended burn-in testing."

...it gives me great pause -- even if the warning is more directed at hardware-based RAID and HBA-based deployments.

And, then when I do an search of "Green" drive buyer feedback on New Egg who have the word "RAID" in their posts -- and read their comments about general drive failure rates and RAID-related problems -- I become further dissuaded.

My application is more mission critical -- and I'd rather spend the money on an enterprise drive that is designed for RAID -- than find myself chasing after a problem that I was so clearly warned to avoid.

At any rate, my original question is really this:

Are there any other highly-rated, low-power, low-heat, enterprise-level drives suitable for software RAID5 deployments that I should be seriously considering -- BESIDES the WD RE4-GP?

Thanks very much for your assistance.

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So to that final question then, the RE4-GP is a very good option. I'd feel very good about that for your use.

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I'd rather not pay the premium either -- but when the manufacturer clearly states at the bottom of their "Green" product page that:

"WD Caviar Green Hard Drives are not recommended for and are not warranted for use in RAID environments..."

"Please consider WD's Enterprise Hard Drives that are specifically designed with RAID-specific, time-limited error recovery (TLER..."

"[which] are tested extensively in 24x7 RAID applications, and include features like enhanced RAFF technology and thermal extended burn-in testing."

...it gives me great pause -- even if the warning is more directed at hardware-based RAID and HBA-based deployments.

The most noticeable difference between enterprise and consumer drives is firmware configuration. Physicaly, the drives can be similar.

In case of RAID applications, enterprise drives implement function called "Error Recovery Control" (Seagate), "Time Limited Error Recovery" (WD), Command Completion Time Limit (Samsung + Hitachi).

Modern hard drives feature an ability to recover from some read/write errors by internally remapping sectors and other forms of self test and recovery. The process for this can sometimes take several seconds or (under heavy usage) minutes, during which time the drive is unresponsive. RAID controllers are designed to recognise a drive which does not respond within a few seconds, and mark it as unreliable, indicating that it should be withdrawn from use and the array rebuilt from parity data. This is a long process, degrades performance, and if more drives fail under the resulting additional workload, it may be catastrophic.

If the drive itself is inherently reliable but has some bad sectors, then TLER and similar features prevent a disk from being unnecessarily marked as 'failed' by limiting the time spent on correcting detected errors before advising the array controller of a failed operation. The array controller can then handle the data recovery for the limited amount involved, rather than marking the entire drive as faulty.

source

This is the reason why it is recommended to use Enterprise drives for HW RAID. Even Consumer drives usually implement Error Recovery Control, but if you enable this feature, it will be disabled after reboot.

Since you want to use SW RAID, you do not need TLER function implemented and using standard drive is possible. Whether it will be WD Caviar Green, Seagate LP or Samsung EcoGreen it is up to you.

Edited by StorageTux

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Get a Samsung F4 5400rpm 2TB, apply the firmware fix (important), connect to a non-RAID controller; HBA, preferably in AHCI mode. Now use you Linux Software RAID on a recent kernel.

The F4 has 4K sectors which is a benefit against BER (Bit-Error-Rate), it also has very high sequential speeds; up to 140MB/s sequential read which is very good for a low-power 5400rpm disk. You would want to use aligned partitions though; or not use any partitions at all, to avoid any alignment issues. Both methods are supported in Linux; feel free to inquire for more details.

Also read this for background on TLER:

http://forums.storagereview.com/index.php/topic/29208-how-to-use-desktop-drives-in-raid-without-tlererccctl/page__p__266337entry266337

Edited by sub.mesa

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Get a Samsung F4 5400rpm 2TB, apply the firmware fix (important), connect to a non-RAID controller; HBA, preferably in AHCI mode. Now use you Linux Software RAID on a recent kernel.

The F4 has 4K sectors which is a benefit against BER (Bit-Error-Rate), it also has very high sequential speeds; up to 140MB/s sequential read which is very good for a low-power 5400rpm disk. You would want to use aligned partitions though; or not use any partitions at all, to avoid any alignment issues. Both methods are supported in Linux; feel free to inquire for more details.

Also read this for background on TLER:

http://forums.storagereview.com/index.php/topic/29208-how-to-use-desktop-drives-in-raid-without-tlererccctl/page__p__266337entry266337

Thanks.

I have spent so much time researching this topic -- that I am now weighing the possibility of 3TB drives.

If I wait any longer -- it will be 4TB drives.

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