[zfs-discuss] Memory Usage

Thomas Burns
Tue, 12 Sep 2006 22:08:55 -0000

>> Also, where do I set arc.c_max?  In etc/system?  Out of
>> curiosity,  why isn''t
>> limiting arc.c_max considered best practice (I just want to make
>> sure  I am
>> not missing something about the effect limiting it will have)?
>> My  guess is
>> that in our case (lots of small groups -- 50 people or less --
>> sharing files
>> over the web)  that file system caches are not that useful.  The
>> small groups
>> mean that no one file gets used that often and, since access is
>> over  the web,
>> their response time will be largely limited by their internet
>> connection.
>
> We don''t want users to need to tune a bunch of knobs to get
> performance
> out of ZFS.  We want it to work well "out of the box".  So we are
> trying
> to discourage using these tunables, and instead figure out what the
> root
> problem is and fix it.  There is really no reason why zfs
shouldn''t be
> able to adapt itself appropriately to the available memory.

Ah, the ZFS philosophy that I love (not have to tune a bunch of knobs)!

Seems like you need a way for the kernal to say "I would like some
memory
back now".  I don''t have the slightest idea how practical that is
though...

BTW -- did I guess right wrt where I need to set arc.c_max (etc/system)?

Thanks,
Tom