Date: Thu, 22 Sep 2016 16:54:52 +0500 From: "Eugene M. Zheganin" <emz@norma.perm.ru> To: freebsd-stable@FreeBSD.org Subject: zfs/raidz and creation pause/blocking Message-ID: <57E3C68C.8060200@norma.perm.ru>
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Hi.
Recently I spent a lot of time setting up various zfs installations, and
I got a question.
Often when creating a raidz on disks considerably big (>~ 1T) I'm seeing
a weird stuff: "zpool create" blocks, and waits for several minutes. In
the same time system is fully responsive and I can see in gstat that the
kernel starts to tamper all the pool candidates sequentially at 100%
busy with iops around zero (in the example below, taken from a live
system, it's doing something with da11):
(zpool create gamestop raidz da5 da7 da8 da9 da10 da11)
dT: 1.064s w: 1.000s
L(q) ops/s r/s kBps ms/r w/s kBps ms/w %busy Name
0 0 0 0 0.0 0 0 0.0 0.0| da0
0 0 0 0 0.0 0 0 0.0 0.0| da1
0 0 0 0 0.0 0 0 0.0 0.0| da2
0 0 0 0 0.0 0 0 0.0 0.0| da3
0 0 0 0 0.0 0 0 0.0 0.0| da4
0 0 0 0 0.0 0 0 0.0 0.0| da5
0 0 0 0 0.0 0 0 0.0 0.0| da6
0 0 0 0 0.0 0 0 0.0 0.0| da7
0 0 0 0 0.0 0 0 0.0 0.0| da8
0 0 0 0 0.0 0 0 0.0 0.0| da9
0 0 0 0 0.0 0 0 0.0 0.0| da10
150 3 0 0 0.0 0 0 0.0 112.6| da11
0 0 0 0 0.0 0 0 0.0 0.0| da0p1
0 0 0 0 0.0 0 0 0.0 0.0| da0p2
0 0 0 0 0.0 0 0 0.0 0.0| da0p3
0 0 0 0 0.0 0 0 0.0 0.0| da1p1
0 0 0 0 0.0 0 0 0.0 0.0| da1p2
0 0 0 0 0.0 0 0 0.0 0.0| da1p3
0 0 0 0 0.0 0 0 0.0 0.0| da0p4
0 0 0 0 0.0 0 0 0.0 0.0| gpt/boot0
0 0 0 0 0.0 0 0 0.0 0.0|
gptid/22659641-7ee6-11e6-9b56-0cc47aa41194
0 0 0 0 0.0 0 0 0.0 0.0| gpt/zroot0
0 0 0 0 0.0 0 0 0.0 0.0| gpt/esx0
0 0 0 0 0.0 0 0 0.0 0.0| gpt/boot1
0 0 0 0 0.0 0 0 0.0 0.0|
gptid/23c1fbec-7ee6-11e6-9b56-0cc47aa41194
0 0 0 0 0.0 0 0 0.0 0.0| gpt/zroot1
0 0 0 0 0.0 0 0 0.0 0.0| mirror/mirror
0 0 0 0 0.0 0 0 0.0 0.0| da1p4
0 0 0 0 0.0 0 0 0.0 0.0| gpt/esx1
The most funny thing is that da5,7-11 are SSD, with a capability of like
30K iops at their least.
So I wonder what is happening during this and why does it take that
long. Because usually pools are creating very fast.
Thanks.
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