Skip site navigation (1)Skip section navigation (2)
Date:      Mon, 19 Sep 2011 16:36:07 +0200
From:      Robert Schulze <rs@bytecamp.net>
To:        freebsd-stable@freebsd.org
Subject:   change in io statistics since updating 8.2-STABLE
Message-ID:  <4E775357.6020104@bytecamp.net>

index | next in thread | raw e-mail

Hello,

like described in another thread, we recently updated a fileserver from 
8.2-STABLE@2011-05-08 to 8.2-STABLE@2011-09-08 (amd64 both). ZPool is 
left at v14, the filesystems at version 3. Nothing in /boot/loader.conf 
or /etc/sysctl.conf has been changed.

We now realize that r/w behaviour has changed on the whole pool.
The l2arc devices (2 SSDs) have decreased in writes from average 10M/sec 
(peaks at 20 M/sec) to <5M/sec.

On the other hand, reads on the disks (2x5 disks raidz2) have increased 
(nearly doubled on each disk).

I suspect, that the cache is somewhat faulty or has become slow, and so 
ZFS decides to read data from main storage instead of the cache. Is 
there another explaination? Are there some defaults of sysctls which 
have been changed from May to September?

with kind regards,
Robert Schulze


home | help

Want to link to this message? Use this
URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?4E775357.6020104>