Re: ZFS L2ARC - incorrect size and abnormal system load on r255173

From: Vitalij Satanivskij <satan_at_ukr.net>
Date: Tue, 22 Oct 2013 17:10:55 +0300
First of all Thank you for help.

As for high load on system, looks like problems with l2arc have litle impact on load comparatively to another just now 

not fully classifed things.

Looks like ower internal software and libs that it use didn't like new VMEM subsystem, at last 
system behavior complitely diferent from 6 month older CURRENT. 

So for now none problem's with l2arc errors.

Will try to understand reason of load and fix or at last ask for help again ^).




Steven Hartland wrote:
SH> First off I just wanted to clarify that you don't need to compression on
SH> dataset for L2ARC to use LZ4 compression, it does this by default as is
SH> not currently configurable.
SH> 
SH> Next up I believe we've found the cause of this high load and I've just
SH> committed the fix to head:
SH> http://svnweb.freebsd.org/base?view=revision&sortby=file&revision=256889
SH> 
SH> Thanks to Vitalij for testing :)
SH> 
SH> Dmitriy if you could test on your side too that would be appreciated.
SH> 
SH>     Regards
SH>     Steve
SH> 
SH> ----- Original Message ----- 
SH> From: "Vitalij Satanivskij" <satan_at_ukr.net>
SH> To: "Allan Jude" <freebsd_at_allanjude.com>
SH> Cc: <freebsd-current_at_freebsd.org>
SH> Sent: Thursday, October 10, 2013 6:03 PM
SH> Subject: Re: ZFS L2ARC - incorrect size and abnormal system load on r255173
SH> 
SH> 
SH> > AJ> Some background on L2ARC compression for you:
SH> > AJ> 
SH> > AJ> http://wiki.illumos.org/display/illumos/L2ARC+Compression
SH> > 
SH> > I'm alredy see it.
SH> > 
SH> > 
SH> > 
SH> > AJ> http://svnweb.freebsd.org/base?view=revision&revision=251478
SH> > AJ> 
SH> > AJ> Are you sure that compression on pool/zfs is off? it would normally
SH> > AJ> inherit from the parent, so double check with: zfs get compression pool/zfs
SH> > 
SH> > Yes, compression turned off on pool/zfs, it's was may time rechecked.
SH> > 
SH> > 
SH> > 
SH> > AJ> Is the data on pool/zfs related to the data on the root pool? if
SH> > AJ> pool/zfs were a clone, and the data is actually used in both places, the
SH> > AJ> newer 'single copy ARC' feature may come in to play:
SH> > AJ> https://www.illumos.org/issues/3145
SH> > 
SH> > No, both pool and pool/zfs have diferent type of data, pool/zfs was created as new empty zfs (zfs create pool/zfs)
SH> > 
SH> > and data was writed to it from another server. 
SH> > 
SH> > 
SH> > Right now one machine work fine with l2arc. This machine without patch for corecting ashift on cache devices.
SH> > 
SH> > At last 3 day's working with zero errors. Another servers with same config similar data, load and so on after 2 day 
SH> > work began report abouy errors.
SH> > 
SH> > 
SH> > AJ> 
SH> > AJ> 
SH> > AJ> 
SH> > AJ> -- 
SH> > AJ> Allan Jude
SH> > AJ> 
SH> > AJ> _______________________________________________
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Received on Tue Oct 22 2013 - 12:11:07 UTC

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