Am 23.12.10 13:09, schrieb Phil Harman:
On 23 Dec 2010, at 11:53, Stephan Budach <stephan.bud...@jvm.de
<mailto:stephan.bud...@jvm.de>> wrote:
Am 23.12.10 12:18, schrieb Phil Harman:
Sent from my iPhone (which had a lousy user interface which makes it
all too easy for a clumsy oaf like me to touch "Send" before I'm
done)...
On 23 Dec 2010, at 11:07, Phil Harman <phil.har...@gmail.com
<mailto:phil.har...@gmail.com>> wrote:
Great question. In "good enough" computing, beauty is in the eye of
the beholder. My home NAS appliance uses mirrorwd IDE and SATA
drives without a dedicated ZIL
device. And for my home SMB and NFS, that's good enough.
I'm sure that even a 7200rpm SATA ZIL would improve things inmy case.
The random I/O requirement for the ZIL is discussed by Adam (and
Chris) here ...
http://dtrace.org/blogs/ahl/2010/11/15/zil-analysis-from-chris-george/
What I find most encouraging is this statement:
"if HDDs and commodity SSDs continue to be target ZIL devices, ZFS
could and should do more to ensure that writes are sequential."
It's not broken, but it is suboptimal, and fixable (apparently) ;)
Yeah - I read through Christopher's article already and it clearly
shows the shortcomings of current flash SSDs as ZIL devices. On the
other hand, if you's be using a DDRdrive as a ZIL device, you'd
pretty lock this zpool to that particular host, since you can't
easily move the zpool onto another host, without moving the DDRdrive
as well or without detaching the ZIL device(s) from the zpool, which
I find a little bit odd.
I am not actually running in a SOHO scenario with my ZFS file server,
since it has to serve up to 200 users on up to 200 zfs volumes in one
zpool, but the actual data traffic is also not that high either. The
traffic is more of small peaks when someone writes back to a file.
Cheers,
budy
Well, your proposed config will improve what each user sees during
their own private burst, and short stroking can only improve things in
the worst case scenario (although it may not be measurable). So why
not give it a spin and report back to the list in the new year?
Ha ha - if no one else has some more input on this, I will definetively
give it a try in jannuary.
Cheers,
budy
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