IHAC with an X4500 (no SSDs) that got burned with huge performance hit when
applying patch 141445-09 (ZVOLs did not correctly implement the SCSI write
cache behavior and given an unfortunate sequence of events write operations to
the iSCSI lun could be lost.)
As a last resort, I suggested that he try snv_134a. Initial testing went very
well, and performance was even better than when they started. However, he now
suspects that OpenSolaris has the same bug as Solaris (CR6770534). In his words:
+++++
Looking at the iostat writing to a comstar volume I only see the flushes.
(missing data means there was no disk I/O for that time period)
r/s w/s kr/s kw/s wait actv wsvc_t asvc_t
%w %b device
Tue May 11 10:47:56 EDT 2010
Tue May 11 10:48:01 EDT 2010
Tue May 11 10:48:06 EDT 2010
Tue May 11 10:48:11 EDT 2010
Tue May 11 10:48:16 EDT 2010
Tue May 11 10:48:21 EDT 2010 0.0 127.6 0.0 609.5 0.0 0.2 0.0
1.3 0 3 c9t0d0 - Flush
Tue May 11 10:48:26 EDT 2010
Tue May 11 10:48:31 EDT 2010
Tue May 11 10:48:36 EDT 2010
Tue May 11 10:48:41 EDT 2010
Tue May 11 10:48:46 EDT 2010
Tue May 11 10:48:51 EDT 2010 0.0 167.8 0.0 785.0 0.0 0.2 0.0
1.3 0 4 c9t0d0 - Flush
Tue May 11 10:48:56 EDT 2010
Tue May 11 10:49:01 EDT 2010
Tue May 11 10:49:06 EDT 2010
Tue May 11 10:49:11 EDT 2010 2.0 0.4 32.4 0.0 0.0 0.0 0.0
0.0 0 0 c9t0d0 - Read Activity
Tue May 11 10:49:16 EDT 2010
Tue May 11 10:49:21 EDT 2010 0.0 156.2 0.0 736.0 0.0 0.2 0.0
1.3 0 3 c9t0d0 - Flush
Tue May 11 10:49:26 EDT 2010
Tue May 11 10:49:31 EDT 2010
Tue May 11 10:49:36 EDT 2010
Tue May 11 10:49:41 EDT 2010
Tue May 11 10:49:46 EDT 2010
Tue May 11 10:49:51 EDT 2010 0.0 166.8 0.0 813.9 0.0 0.2 0.0
1.4 0 4 c9t0d0 - Flush
Tue May 11 10:49:56 EDT 2010
Tue May 11 10:50:01 EDT 2010
Tue May 11 10:50:06 EDT 2010
Tue May 11 10:50:11 EDT 2010
Tue May 11 10:50:16 EDT 2010
Tue May 11 10:50:21 EDT 2010 0.0 174.4 0.0 802.2 0.0 0.2 0.0
1.3 0 4 c9t0d0 - Flush
Tue May 11 10:50:26 EDT 2010
Tue May 11 10:50:31 EDT 2010 2.0 0.4 32.4 0.0 0.0 0.0 0.0
0.0 0 0 c9t0d0 - Read activity
Tue May 11 10:50:36 EDT 2010
Tue May 11 10:50:41 EDT 2010
Tue May 11 10:50:46 EDT 2010
Tue May 11 10:50:51 EDT 2010 0.0 148.6 0.0 719.2 0.0 0.2 0.0
1.2 0 3 c9t0d0 - Flush
So, what am I missing? The ZIL is enabled - I checked:
# mdb -kw
> zil_disable/X
zil_disable:
zil_disable: 0
I disabled it and didn't get any better performance and see the same io pattern.
>From what I can see the COMSTAR iSCSI target suffers from the same possible
>loss of data bug the pre-patched iscsi target daemon suffers from.
Is there any way you can verify I have everything right. Do I have to configure
COMSTAR to use the ZIL?
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