Asynchronous writing to zvols (ZFS)

[Peter Schuller]

Hello,

I was finally playing around with iSCSI, having never used it before. For 
convenience, and also because it may be a future use case for real use, I 
used zvols for my targets.

I could not get write speed above roughly 1 MB/second even in simple cases 
like dd:ing with an 8 MB block size, with the zvol:s on a 6-disk raidz2. The 
individual disk utilization of constituent drives remains small (< 3%). 
Switching to a memory disk target yielded expected performance 
characteristics.

I notice that there were confirmed issues with writes to zvol:s:

   http://bugs.opensolaris.org/bugdatabase/view_bug.do?bug_id=6496356
   http://bugs.opensolaris.org/bugdatabase/view_bug.do?bug_id=6496344

The problem is that I'm not really sure how to translate "snv_59" into 
something that I can compare with the version of ZFS in FreeBSD. Do the 
above "bugs" still apply to the ZFS version in FreeBSD, or am I hitting 
something else?

-- 
/ Peter Schuller

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