ARC "pressured out", how to control/stabilize ? (reformatted to text/plain)

[Vitalij Satanivskij]

Get first result's while testing l2 without compression 

Memory leak is not seen for now ( system working only 20 hours) but 
zfs stats saying that l2 degraded 

output of zfs-stats -L: 

------------------------------------------------------------------------
ZFS Subsystem Report                            Tue Feb 11 16:34:43 2014
------------------------------------------------------------------------

L2 ARC Summary: (DEGRADED)
        Passed Headroom:                        3.81m
        Tried Lock Failures:                    79.52m
        IO In Progress:                         9
        Low Memory Aborts:                      235
        Free on Write:                          54.37k
        Writes While Full:                      9.68k
        R/W Clashes:                            2.82k
        Bad Checksums:                          211.94k
        IO Errors:                              0
        SPA Mismatch:                           58.33m

L2 ARC Size: (Adaptive)                         243.32  GiB
        Header Size:                    0.36%   895.11  MiB

L2 ARC Evicts:
        Lock Retries:                           45
        Upon Reading:                           0

L2 ARC Breakdown:                               38.15m
        Hit Ratio:                      17.79%  6.79m
        Miss Ratio:                     82.21%  31.36m
        Feeds:                                  88.88k

L2 ARC Buffer:
        Bytes Scanned:                          292.58  TiB
        Buffer Iterations:                      88.88k
        List Iterations:                        5.63m
        NULL List Iterations:                   17.26k

L2 ARC Writes:
        Writes Sent: (FAULTED)                          77.95k
          Done Ratio:                   100.00% 77.95k
          Error Ratio:                  0.00%   0

------------------------------------------------------------------------

As you can see we have Bad Checksums:                          211.94k and growing 

and also 
        Writes Sent: (FAULTED)                          77.95k
          Done Ratio:                   100.00% 77.95k



Another question: Please provide revision number of arc.c against which was diff created (http://people.freebsd.org/~avg/l2arc-b_tmp_cdata-diag.2.patch)
Because in version in head have some small diferent's and I need manualy aply patch.

Thank you.




Vitalij Satanivskij wrote:
VS> Dear Andriy and FreeBSD community,
VS> 
VS> 
VS> For now I begin testing l2 cache without compression (with you path provided in last messages) in production. 
VS> 
VS> I will test the new patch on the test server first, and then if all is ok on one of the production servers.
VS> 
VS> 
VS> Andriy Gapon wrote:
VS> AG> on 07/02/2014 11:11 Andriy Gapon said the following:
VS> AG> > on 05/02/2014 14:22 Vitalij Satanivskij said the following:
VS> AG> >> Dear Andriy and FreeBSD community,
VS> AG> >>
VS> AG> >> Ok. I'm get coredump on panic.
VS> AG> >>
VS> AG> >> What else i need to do?
VS> AG> > 
VS> AG> > 
VS> AG> > Vitalij, Vladimir,
VS> AG> > 
VS> AG> > I have been able to reproduce the leak at work, so now I have full access to all
VS> AG> > debugging information that I need.  Thank you for your testing and reports.
VS> AG> > 
VS> AG> > I have reported my observations to OpenZFS developers.  It looks like the author
VS> AG> > of L2ARC compression code is too busy right now to produce a fix.
VS> AG> > Unfortunately, I am not very familiar with the L2ARC code, so I can not promise
VS> AG> > to produce a patch soon.
VS> AG> 
VS> AG> I've been able to spend some time on this issue.
VS> AG> Could you please try the following patch?
VS> AG> http://people.freebsd.org/~avg/l2arc-b_tmp_cdata-diag.2.patch
VS> AG> It obsoletes all previous patches from me.
VS> AG> 
VS> AG> -- 
VS> AG> Andriy Gapon
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