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Warner

21:32

Anyone have any thoughts on Linux software raid and TLER?

Zoredache

what do you mean?

Warner

Time-Limited Error Recovery

Time-Limited Error Recovery (TLER) is a name used by Western Digital for a hard drive feature that allows improved error handling in a RAID environment. In some cases, there is a conflict as to whether error handling should be undertaken by the hard drive or by the RAID controller, which leads to drives being marked as unusable and significant performance degradation, when this could otherwise have been avoided. Similar technologies are called Error Recovery Control (ERC), used by competitor Seagate, and Command Completion Time Limit (CCTL), used by Samsung and Hitachi. Overview Modern ha...

I'm curious if commodity disks that do not have TLER will have the same issues in software RAID as they will in hardware RAID.

Ah, finally found something more intelligent..

markmail.org/thread/…

Zoredache

21:47

yes, they have the same issues.

I am not seeing a really good answer on that link. There seems to be a lot of conflicting opinions/information.

Warner

Indeed, some of the best I've found and I've been searching for a while.

Based on that, I'd lean towards having TLER enabled. Or otherwise, be willing to accept the possibility of your drive being popped out when it's good or be willing to accept lock-ups on error.

Zoredache

I do know I have seen non-tler drives dropped from a linux RAID on my home setup, and still test as good, and not show a significant number of errors through SMART...

Warner

It's frustrating.

I shouldn't have to buy an expensive disk to run a decent software RAID at home.

Zoredache

But then the drives where also from the that batch of seagate 1.5 drives that where really broken with RAID setups.

What type of RAID where you planning? A RAID1/10 or a 5/6?

Warner

forums.storagereview.com/index.php/topic/28333-tler-cctl

Check out "breakthrough 1"

I have a RAID5 with a failed disk right now I'm considering, which I want to replace with an additional RAID1. But I want to buy disks I can trust. ;)

Zoredache

21:57

You have read the articles about RAID5 being dead?

zdnet.com/blog/storage/why-raid-5-stops-working-in-2009/162

With drives being so cheap and questionably reliable these days I have pretty much given up on an striping based RAID (5/6) and only go for 1 or 10...

Warner

Yea, definitely. The RAID5 is 500GB disks at home.

I only did RAID5 as a stop-gap because they were so tiny.

I hate RAID5. Totally on board. ;)

I typically only use RAID1 or 1+0. I'd consider RAID6 in a special situation.

Zoredache

Anyway, I think you can somewhat safe with cheap drives as long as you are prepared for a failure of some sort. The tricky part is finding a good backup system that can backup a larger RAID and fit within a typical home network budget..

Warner

What I generally do is categorize data but I'm still refining my home strategy.

Zoredache

cloud storage gets expensive for large amounts of data, and your ISP will probably cap you anyway. Tape drives are expensive, and hard drives aren't very reliable...

Warner

Important documents, et cetera, will take substantially less space than media and other more easily replaceable data.

I plan on doing a crypto loopback and scping to an off-site server.

ISP, cap? Ha. ;) Only Comcast does that craziness.

Zoredache

22:10

I thought Time-Warner did as well..