Re: Btrfs RAID-10 performance

8 Sep 2020

      Thanks for the tips!
Dne 07.09.2020 v 15:24 Scott Q. napsal(a):
...

I assume that's a 2U format -24 bays. You only have 1 raid card for
all 24 disks ? Granted you only have 16, but usually you should assign 1
card per 8 drives. In our standard 2U chassis we have 3 hba's per 8
drives. Your backplane should support that.

Exactly. And what's the reason/bottleneck? PCIe or card throughput?
...

Add more drives

We can add 2 next drives, and we actually did yesterday, but we keep
free slots to be able replace drives by double-capacity ones.
...

Get a pci nvme ssd card and move the indexes/control/sieve files there.

It complicates current backup and restore a little bit, but I'll
probably try that.
Thank you,
Milo
...
On Monday, 07/09/2020 at 08:16 Miloslav Hůla wrote:
Dne 07.09.2020 v 12:43 Sami Ketola napsal(a):
 >> On 7. Sep 2020, at 12.38, Miloslav Hůla &lt;miloslav.hula@gmail.com
&lt;mailto:miloslav.hula@gmail.com>> wrote:
 >>
 >> Hello,
 >>
 >> I sent this into the Linux Kernel Btrfs mailing list and I got
reply: "RAID-1 would be preferable"
(https://lore.kernel.org/linux-btrfs/7b364356-7041-7d18-bd77-f60e0e2e2112@lechevalier.se/T/).
May I ask you for the comments as from people around the Dovecot?
 >>
 >>
 >> We are using btrfs RAID-10 (/data, 4.7TB) on a physical
Supermicro server with Intel(R) Xeon(R) CPU E5-2620 v4 @ 2.10GHz and
125GB of RAM. We run 'btrfs scrub start -B -d /data' every Sunday as
a cron task. It takes about 50 minutes to finish.
 >>
 >> # uname -a
 >> Linux imap 4.9.0-12-amd64 #1 SMP Debian 4.9.210-1 (2020-01-20)
x86_64 GNU/Linux
 >>
 >> RAID is a composition of 16 harddrives. Harddrives are connected
via AVAGO MegaRAID SAS 9361-8i as a RAID-0 devices. All harddrives
are SAS 2.5" 15k drives.
 >>
 >> Server serves as a IMAP with Dovecot 2.2.27-3+deb9u6, 4104
accounts, Mailbox format, LMTP delivery.
 >
 > does "Mailbox format" mean mbox?
 >
 > If so, then there is your bottleneck. mbox is the slowest
possible mailbox format there is.
 >
 > Sami

Sorry, no, it is a typo. We are using "Maildir".

"doveconf -a" attached

Milo