zfs discuss - Jul 2006 - howto reduce ?zfs introduced? noise

Hi,

after switching over to zfs from ufs for my ~/ at home, I am a little bit
disturbed by the noise the disks are making. To be more precise, I always have
thunderbird and firefox running on my desktop and either or both seem to be
writing to my ~/ at short intervals and ZFS flushes these transactions at
intervals about 2-5 seconds to the disks. In contrast UFS seems to be doing a
little bit more aggressive caching, which reduces disk noise.

I didn''t really track down who is the offender and what is the precise
reason. I only know that the noise disappears as soon as I close Thunderbird and
Firefox. So maybe there is an easy way to solve this problem at the application
level. And anyway I want to move my $HOME to more silent disks.

But I am curious, if I am the only one who observed this behaviour? Maybe there
is even an easy way to reduce this noise. Additionally, I''d guess that
moving the heads of the disks all the time, won''t make the disks last
any longer...

Cheers,
Tom
 
 
This message posted from opensolaris.org

I am seeing the same behavior on my SunBlade 2500 while running firefox. I think
my disks are
quieter than yours though, because I don''t really notice the difference
that much.
 
 
This message posted from opensolaris.org

Hello Thomas,

try to set txg_time via mdb to 60 - this shuld maqke ZFS to "flush"
every 60s

-- 
Best regards,
 Robert                            mailto:rmilkowski at task.gda.pl
                                       http://milek.blogspot.com

Quoth Thomas Maier-Komor on Thu, Jul 13, 2006 at 04:19:11AM
-0700:
> after switching over to zfs from ufs for my ~/ at home, I am a little
> bit disturbed by the noise the disks are making. To be more precise,
> I always have thunderbird and firefox running on my desktop and either
> or both seem to be writing to my ~/ at short intervals and ZFS flushes
> these transactions at intervals about 2-5 seconds to the disks. In
> contrast UFS seems to be doing a little bit more aggressive caching,
> which reduces disk noise.
I''d bet that this is due to your applications repeatedly reading some
file, for which ZFS updates the atime, which requires writing more
blocks than with UFS.  In which case you could fix it by mounting with
noatime, but that''s probably not a great idea.


David

Thanks Robert,

that''s exactly what I was looking for. I will try it when I come back
home tomorrow. Is it possible to set this value in /etc/system, too?

Cheers,
Tom
 
 
This message posted from opensolaris.org

I have tested it, and it is _much_ better now. Unfortunately adding "set
txg_time = 60" in /etc/system does not set this value upon system startup.
It only works using mdb at runtime. Do you have an idea, what might be wrong?

Cheers,
Tom
 
 
This message posted from opensolaris.org

Did you write your /etc/system entry as follows?

set zfs:txg_time=60

the txg_time parameter belongs to the zfs module, so you have to prefix 
the module name.

Thanks,
Zoram


Thomas Maier-Komor wrote:
> I have tested it, and it is _much_ better now. Unfortunately adding
"set txg_time = 60" in /etc/system does not set this value upon system
startup. It only works using mdb at runtime. Do you have an idea, what might be
wrong?
> 
> Cheers,
> Tom
>  
>  
> This message posted from opensolaris.org
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> zfs-discuss mailing list
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-- 
Zoram Thanga, Sun Cluster Development.