SMR drives / RAID 5 and 6 levels

[MvL (Marcel)]

Hi Community,

I have a question regarding SMR drives. Is it already possible to use these drives with BTRFS? A other question what is the status of the RAID 5, 6 levels?

[phillxnet (Philip Guyton)]

@MvL Welcome to the Rockstor community. We have an existing thread that may help on the SMR question:

SMR Drives still a problem?

What's the status of SMR drivies and the Linux kernel/BTRFS these days? I seem to recall it didn't work to well in the past, has this been resolved or should they still be avoided? Slow write speed isn't really an issue as my rockstor box is remote (I.e incoming is limited by WAN speeds anyway), having the drives drop offline however would be. I have a 3TB drive I need to replace at some point (showing a few bad sectors), can't decide to go for a raid5 with 4TB-5TB drives or a raid1 with 2…

I think it comes down to if they are host or self managed disks but I don’t know. That thread and the links it contains may help with this question.
And on the btrfs RAID 5, 6 question we also have a rather inactive but still useful thread:

Question about RAID5/6 stability

Hello, I have been following Rockstor for a couple of months with great interest. Now I have purchased a second hand rackmount server to hold some left over hdd's and I want to use Rockstor on it. My server is an IBM / Xyratex HS-1235e, which is a rebranded Intel SSR212MC2 reference design. I installed Rockstor on it and aside from a few small issues (for which I will open a new discussion) it is working great. This server has 12 3.5" bays and I have 10 2tb disks. I would like to use raid 6,…

It might be worth waking that thread up if the info you find doesn’t answer you question. I do know that raid 5/6 balances are currently very much under performing time wise in comparison with raid 1 / and 10, ie taking days to complete on large file systems… If in any double I would suggest you go for raid 1 or 10 for the time being.

Hope that helps.

[MvL (Marcel)]

Thank you for your kind words and the links!

[haoto]

I’ve been using a Seagate SMR drive for a week, and all things seem to be going well so far. There was a bug affecting SMR drives that was fixed in kernel version 4.4, so you should probably update your kernel in case you’re using an older install.

BTW, I think all the common SMR drives (Seagate 3.5" 8TB and 2.5" 4TB ones) are drive-managed.

[MvL (Marcel)]

haoto @haoto , thank you for your reply.

I’ve been using a Seagate SMR drive for a week, and all things seem to be going well so far. There was a bug affecting SMR drives that was fixed in kernel version 4.4, so you should probably update your kernel in case you’re using an older install.

Okay, clear. I have 4 Seagate Archive 8TB (SMR) drives. That is also the one you use?

BTW, I think all the common SMR drives (Seagate 3.5" 8TB and 2.5" 4TB ones) are drive-managed.

You mean self-managed I assume?

[haoto]

Hi @MvL,

Yes, self-managed as in it’s transparent to the host. I’m actually using the Seagate 4TB 2.5" one, but all the information I found was about the one you have.

[MvL (Marcel)]

@haoto thanks for answering!

I’m subscribed to the btrfs mailing list and there was some discussion about RAID 5 / 6. I’m getting the impression RAID 5 / 6 is not production ready yet.