ZFS Filesystem Post: 302953494

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Operating Systems Solaris ZFS Filesystem Post 302953494 by achenle on Friday 28th of August 2015 02:19:09 PM

08-28-2015

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Quote:

Originally Posted by jlliagre

@achenle Yes, the ARC size should not be left unlimited when running an Oracle database. 1GB seems to be quite aggressive with a 32GB server though. That might waste memory and will likely affect overall performance.

Shouldn't impact performance at all. Database IO isn't going to go through the ARC - it'll be either direct IO or synchronous. Log files are generally streamed and forgotten about, so not having cached data from writes there isn't a big deal. And once the cache gets beyond a few tens of MB, the effective filesystem cache hit rate isn't going to change much anyway given the usage patterns on a pure DB server.

In my experience, performance often gets better because there's actually some free RAM on the server, so response to transient demands is a helluva lot faster.

If you want the DB to cache data, create a larger-than-default SGA for that, and create larger buffer and redo log pools in it as needed.

To get the max performance out of an Oracle DB running on Solaris, you really do have to get the ZFS ARC out of the way. (And you also have to be really careful about how your DB job processes behave - you do not want to have your DB trying to start or stop several thousand processes all at the same time...)

(I spent a few years consulting for a customer using multiple large Oracle RAC clusters on SPARC servers - one of my main jobs was getting the best possible performance out of the servers. Oracle on Solaris is as good as it gets for performance and reliability - yes, better than Linux for a lot of reasons - but there are some quirks - and the ARC is one of them.)

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x11perfcomp

x11perfcomp(1X) 														   x11perfcomp(1X)

NAME

       x11perfcomp - X11 server performance comparison program

SYNOPSIS

       x11perfcomp [-r	| -ro] [-l label_file] files

OPTIONS

       x11perfcomp  accepts  the  options listed below: Specifies that the output should also include relative server performance.  Specifies that
       the output should include only relative server performance.  Specifies a label file to use.

DESCRIPTION

       The x11perfcomp program merges the output of several x11perf(1X) runs into a nice tabular format.  It takes the results in each file, fills
       in  any	missing  test  results if necessary, and for each test shows the objects/second rate of each server. If invoked with the -r or -ro
       options, it shows the relative performance of each server to the first server.

       Normally, x11perfcomp uses the first file specified to determine which specific tests it should report on.  Some (non-DEC  :)  servers  may
       fail  to  perform  all  tests.	In  this case, x11perfcomp automatically substitutes in a rate of 0.0 objects/second. Since the first file
       determines which tests to report on, this file must contain a superset of the tests reported in the  other  files,  else  x11perfcomp  will
       fail.

       You  can provide an explicit list of tests to report on by using the -l switch to specify a file of labels.  You can create a label file by
       using the -label option in x11perf.

X DEFAULTS

       There are no X defaults used by this program.

SEE ALSO

       X(1X), x11perf(1X)

AUTHORS

       Mark Moraes wrote the original scripts to compare servers. Joel McCormack just munged them together a bit.

																   x11perfcomp(1X)