Thx all, I understand now.
BR, Jeffry
>
> if an application requests a synchronous write then it is commited to
> ZIL immediately, once it is done the IO is acknowledged to application.
> But data written to ZIL is still in memory as part of an currently open
> txg and will be committed to a pool
On 16/01/2010 00:09, Jeffry Molanus wrote:
-Original Message-
From: neil.per...@sun.com [mailto:neil.per...@sun.com]
I think you misunderstand the function of the ZIL. It's not a journal,
and doesn't get transferred to the pool as of a txg. It's only ever
written except
a
> -Original Message-
> From: neil.per...@sun.com [mailto:neil.per...@sun.com]
> I think you misunderstand the function of the ZIL. It's not a journal,
> and doesn't get transferred to the pool as of a txg. It's only ever
> written except
> after a crash it's read to do replay. See:
>
>
On Fri, Jan 15, 2010 at 1:59 PM, Jeffry Molanus
wrote:
>
>> Sometimes people get confused about the ZIL and separate logs. For
>> sizing purposes,
>> the ZIL is a write-only workload. Data which is written to the ZIL is
>> later asynchronously
>> written to the pool when the txg is committed.
>
>
I think Y is such a variable and complex number it would be difficult to give a
rule of thumb, other than to 'test with your workload'.
My server, having three, five disk raidzs (striped) and an intel x25-e as a zil
can fill my two G ethernet pipes over NFS (~200MBps) during mostly sequential
On 01/15/10 12:59, Jeffry Molanus wrote:
Sometimes people get confused about the ZIL and separate logs. For
sizing purposes,
the ZIL is a write-only workload. Data which is written to the ZIL is
later asynchronously
written to the pool when the txg is committed.
Right; the tgx needs time t
> Sometimes people get confused about the ZIL and separate logs. For
> sizing purposes,
> the ZIL is a write-only workload. Data which is written to the ZIL is
> later asynchronously
> written to the pool when the txg is committed.
Right; the tgx needs time to transfer the ZIL.
> The ZFS wri
On Jan 14, 2010, at 4:02 PM, Richard Elling wrote:
> That is a simple performance model for small, random reads. The ZIL
> is a write-only workload, so the model will not apply.
BTW, it is a Good Thing (tm) the small, random read model does not
apply to the ZIL.
-- richard
On Jan 14, 2010, at 3:59 PM, Ray Van Dolson wrote:
> On Thu, Jan 14, 2010 at 03:55:20PM -0800, Ray Van Dolson wrote:
>> On Thu, Jan 14, 2010 at 03:41:17PM -0800, Richard Elling wrote:
Consider a pool of 3x 2TB SATA disks in RAIZ1, you would roughly
have 80 IOPS. Any info about the relat
On Thu, Jan 14, 2010 at 03:55:20PM -0800, Ray Van Dolson wrote:
> On Thu, Jan 14, 2010 at 03:41:17PM -0800, Richard Elling wrote:
> > > Consider a pool of 3x 2TB SATA disks in RAIZ1, you would roughly
> > > have 80 IOPS. Any info about the relation between ZIL <> pool
> > > performance? Or will th
On Thu, Jan 14, 2010 at 03:41:17PM -0800, Richard Elling wrote:
> > Consider a pool of 3x 2TB SATA disks in RAIZ1, you would roughly
> > have 80 IOPS. Any info about the relation between ZIL <> pool
> > performance? Or will the ZIL simply fill up and performance drops
> > to pool speed?
>
> The Z
On Jan 14, 2010, at 10:58 AM, Jeffry Molanus wrote:
> Hi all,
>
> Are there any recommendations regarding min IOPS the backing storage pool
> needs to have when flushing the SSD ZIL to the pool?
Pedantically, as many as you can afford :-) The DDRdrive folks sell IOPS at
200 IOPS/$.
Sometimes
>
> There are different kinds of "IOPS". The expensive ones are random
> IOPS whereas sequential IOPS are much more efficient. The intention
> of the SSD-based ZIL is to defer the physical write so that would-be
> random IOPS can be converted to sequential scheduled IOPS like a
> normal write.
On Thu, 14 Jan 2010, Jeffry Molanus wrote:
Are there any recommendations regarding min IOPS the backing storage
pool needs to have when flushing the SSD ZIL to the pool? Consider a
pool of 3x 2TB SATA disks in RAIZ1, you would roughly have 80 IOPS.
Any info about the relation between ZIL <> po
Hi all,
Are there any recommendations regarding min IOPS the backing storage pool needs
to have when flushing the SSD ZIL to the pool? Consider a pool of 3x 2TB SATA
disks in RAIZ1, you would roughly have 80 IOPS. Any info about the relation
between ZIL <> pool performance? Or will the ZIL sim
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