RFT: ZFS MFC

[Nikolay Denev]

On May 27, 2009, at 7:38 AM, Kip Macy wrote:

> On Tue, May 26, 2009 at 9:51 AM, Kai Gallasch <gallasch at free.de>  
> wrote:
>> Kip Macy wrote:
>>> I've MFC'd ZFS v13 to RELENG_7 in a work branch. Please test if  
>>> you can.
>>>
>>> http://svn.freebsd.org/base/user/kmacy/ZFS_MFC/
>>>
>>> The standard disclaimers apply. This has only been lightly tested  
>>> in a
>>> VM. Please do not use it with data you care about at this time.
>>>
>>
>> Hi.
>>
>> http://www.freebsd.org/cgi/cvsweb.cgi/src/sys/cddl/contrib/opensolaris/common/zfs/zfs_prop.c
>>
>> So ZFS v13 is now part of RELENG_7 MAIN.
>> Did you receive any negative feedback until now?
>>
>> zpool upgrade:
>> Should a ZFS v6 pool be upgraded through 'zpool upgrade' while in  
>> use?
>>
>> loader.conf:
>> My old loader.conf (7.2-STABLE-amd64) settings for zfs:
>>
>> vm.kmem_size="3072M"
>> vm.kmem_size_max="3072M"
>> vfs.zfs.arc_min="120795878"
>> vfs.zfs.arc_max="2899101078"
>> # more stability?
>> vfs.zfs.prefetch_disable=1
>>
>> Is there a need to keep the old (painfully found :) known to work
>> settings when upgrading from ZFS v6 to v13 on RELENG_7, because in  
>> your
>> commit message I read: "- the arc now experiences backpressure from  
>> the
>> vm (which can be too much - but this allows ZFS to work without any
>> tunables on amd64)"
>>
>
> Machines with less than 4GB, especially those with workloads with poor
> locality,  should have prefetch disabled. You should not need the
> other tunables on amd64 (i386 is both a lower priority and a harder
> problem). When reporting problems report them with the tunables
> removed as well as whatever your existing tunables are.
>
>
> -Kip


How about just tuning down zfetch a bit?

I'm currently using these settings :

vfs.zfs.zfetch.array_rd_sz=65536
vfs.zfs.zfetch.block_cap=8
vfs.zfs.zfetch.max_streams=2

With them my machine seems to work better than with prefetch totally  
disabled,
and does not do excessive IO like it does with the default prefetch  
settings while for example downloading/seeding
a torrent file.

But does this reduce memory usage too?

Regards,
Niki Denev

-------------- next part --------------
A non-text attachment was scrubbed...
Name: PGP.sig
Type: application/pgp-signature
Size: 195 bytes
Desc: This is a digitally signed message part
Url : http://lists.freebsd.org/pipermail/freebsd-fs/attachments/20090528/d06abfde/PGP.pgp