Help with ZFS arc cache Post: 302479938

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Operating Systems Solaris Help with ZFS arc cache Post 302479938 by jim mcnamara on Monday 13th of December 2010 10:48:26 AM

12-13-2010

Registered User

Correct me where I missed the point - the system allocates 'unused' memory which it gives up when needed. You still have lots of free pages. This an m4000:

Code:

# echo ::memstat |mdb -k
Page Summary                Pages                MB  %Tot
------------     ----------------  ----------------  ----
Kernel                     398633              3114    5%
Anon                      1074821              8397   13%
Exec and libs               58856               459    1%
Page cache                6013479             46980   73%
Free (cachelist)           229681              1794    3%
Free (freelist)            459750              3591    6%

Total                     8235220             64337
Physical                  8213603             64168

Is page cache is out of control? No. The system is doing to this m4000 exactly what you see on your box. Using idle memory to good advantage.

Are you experiecing problems? Really sluggish performance, lots of swapping?

---------- Post updated at 08:48 ---------- Previous update was at 08:42 ----------

Here found it - the Evil Tuning Guide

ZFS Evil Tuning Guide - Siwiki

Read the arc cache section.

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LEARN ABOUT HPUX

dbc_min_pct

dbc_max_pct(5)							     OBSOLETED							    dbc_max_pct(5)

NAME

       dbc_max_pct, dbc_min_pct, bufcache_max_pct, bufpages, nbuf - OBSOLETED kernel tunable parameter

DESCRIPTION

       These tunables have been obsoleted and removed.	Do not make any changes to these tunables, as they have no effect on the kernel.

       Use the file cache tunables and (see filecache_max(5)).

       In  previous  releases, the tunables and were used to set limits to the dynamic buffer cache, and the tunables and were used for tuning the
       buffer cache when a static cache was desired.

       This release of HP-UX offers improved file caching technology and improved physical memory control associated to  caching  file	I/O  data.
       The  number  of tunable parameters used to control file caching memory usage is reduced from five to two, and previous usability issues are
       addressed.

   Restrictions on Changing
       These tunables should not be modified.  Attempting to tune any of the obsolete buffer cache tunables, or results in an error.

       Use the tunables and to set limits on the file cache.  Note that, on a any given system, the optimum values of these two new  tunables  are
       not necessarily equivalent to the optimum values of the obsolete buffer cache tunable values in the older systems.  You should first deter-
       mine if the new default values yield acceptable performance on your system, before attempting to change the values of the  new  file  cache
       tunables.

AUTHOR

       and were developed by HP.

SEE ALSO

       filecache_max(5).

							     Kernel Tunable Parameter						    dbc_max_pct(5)