zfs discuss - Jan 2009 - SSD drives in Sun Fire X4540 or X4500 for dedicated ZIL device

We''re evaluating the possibility of speeding up NFS operations of our 
X4540s with dedicated log devices. What we are specifically evaluating 
is replacing 1 or two of our spare sata disks with sata SSDs.

Has anybody tried using SSD device(s) as dedicated ZIL devices in a 
X4540? Are there any known technical issues with using a SSD in a X4540?

-Greg

I don''t have an x4540, and this may not be relevant to your usage, but
the concern I would have would be how this is going to affect throughput.  An
x4540 can stream data to and from the disk far faster than any SATA SSD, or even
a pair of SATA SSD''s can.  I''d be nervous about improving my
latency at the cost of throughput.

I''ve read that ZFS is supposed to stream large writes directly to disk
to avoid this, but I''ve also read about this not always working (no
links I''m afraid, this was a while ago).

For an x4540, what I''d be watching are the PCIe SSD devices, and hoping
that either Fusion-io or Micron release Solaris drivers for them.
-- 
This message posted from opensolaris.org

However, now I''ve written that, Sun use SATA (SAS?) SSD''s in
their high end fishworks storage, so I guess it definately works for some use
cases.
-- 
This message posted from opensolaris.org

On Thu, 22 Jan 2009, Ross wrote:
> However, now I''ve written that, Sun use SATA (SAS?) SSD''s
in their
> high end fishworks storage, so I guess it definately works for some 
> use cases.
But the "fishworks" (Fishworks is a development team, not a product) 
write cache device is not based on FLASH.  It is based on DRAM.  The 
difference is like night and day. Apparently there can also be a read 
cache which is based on FLASH.

Bob
=====================================Bob Friesenhahn
bfriesen at simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/

If i''m not mistaken (and somebody please correct me if i''m
wrong), the
Sun 7000 series storage appliances (the Fishworks boxes) use enterprise 
SSDs, with dram caching. One such product is made by STEC.

My understanding is that the Sun appliances use one SSD for the ZIL, and 
one as a read cache. For the 7210 (which is basically a Sun Fire X4540), 
that gives you 46 disks and 2 SSDs.

-Greg


Bob Friesenhahn wrote:
> On Thu, 22 Jan 2009, Ross wrote:
> 
>> However, now I''ve written that, Sun use SATA (SAS?)
SSD''s in their
>> high end fishworks storage, so I guess it definately works for some 
>> use cases.
> 
> But the "fishworks" (Fishworks is a development team, not a
product)
> write cache device is not based on FLASH.  It is based on DRAM.  The 
> difference is like night and day. Apparently there can also be a read 
> cache which is based on FLASH.
> 
> Bob
> =====================================> Bob Friesenhahn
> bfriesen at simple.dallas.tx.us,
http://www.simplesystems.org/users/bfriesen/
> GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/
> 
> _______________________________________________
> zfs-discuss mailing list
> zfs-discuss at opensolaris.org
> http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
> 
>

That''s my understanding too.  One (STEC?) drive as a write cache,
basically a write optimised SSD.  And cheaper, larger, read optimised
SSD''s for the read cache.

I thought it was an odd strategy until I read into SSD''s a little more
and realised you really do have to think about your usage cases with
these.  SSD''s are very definitely not all alike.


On Fri, Jan 23, 2009 at 4:33 PM, Greg Mason <gmason at msu.edu>
wrote:
> If i''m not mistaken (and somebody please correct me if
i''m wrong), the Sun
> 7000 series storage appliances (the Fishworks boxes) use enterprise SSDs,
> with dram caching. One such product is made by STEC.
>
> My understanding is that the Sun appliances use one SSD for the ZIL, and
one
> as a read cache. For the 7210 (which is basically a Sun Fire X4540), that
> gives you 46 disks and 2 SSDs.
>
> -Greg
>
>
> Bob Friesenhahn wrote:
>>
>> On Thu, 22 Jan 2009, Ross wrote:
>>
>>> However, now I''ve written that, Sun use SATA (SAS?)
SSD''s in their high
>>> end fishworks storage, so I guess it definately works for some use
cases.
>>
>> But the "fishworks" (Fishworks is a development team, not a
product) write
>> cache device is not based on FLASH.  It is based on DRAM.  The
difference is
>> like night and day. Apparently there can also be a read cache which is
based
>> on FLASH.
>>
>> Bob
>> =====================================>> Bob Friesenhahn
>> bfriesen at simple.dallas.tx.us,
http://www.simplesystems.org/users/bfriesen/
>> GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/
>>
>> _______________________________________________
>> zfs-discuss mailing list
>> zfs-discuss at opensolaris.org
>> http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
>>
>>
>

This is correct, and you can read about it here:

  http://blogs.sun.com/ahl/entry/fishworks_launch

Adam

On Fri, Jan 23, 2009 at 05:03:57PM +0000, Ross Smith
wrote:
> That''s my understanding too.  One (STEC?) drive as a write cache,
> basically a write optimised SSD.  And cheaper, larger, read optimised
> SSD''s for the read cache.
> 
> I thought it was an odd strategy until I read into SSD''s a little
more
> and realised you really do have to think about your usage cases with
> these.  SSD''s are very definitely not all alike.
> 
> 
> On Fri, Jan 23, 2009 at 4:33 PM, Greg Mason <gmason at msu.edu>
wrote:
> > If i''m not mistaken (and somebody please correct me if
i''m wrong), the Sun
> > 7000 series storage appliances (the Fishworks boxes) use enterprise
SSDs,
> > with dram caching. One such product is made by STEC.
> >
> > My understanding is that the Sun appliances use one SSD for the ZIL,
and one
> > as a read cache. For the 7210 (which is basically a Sun Fire X4540),
that
> > gives you 46 disks and 2 SSDs.
> >
> > -Greg
> >
> >
> > Bob Friesenhahn wrote:
> >>
> >> On Thu, 22 Jan 2009, Ross wrote:
> >>
> >>> However, now I''ve written that, Sun use SATA (SAS?)
SSD''s in their high
> >>> end fishworks storage, so I guess it definately works for some
use cases.
> >>
> >> But the "fishworks" (Fishworks is a development team,
not a product) write
> >> cache device is not based on FLASH.  It is based on DRAM.  The
difference is
> >> like night and day. Apparently there can also be a read cache
which is based
> >> on FLASH.
> >>
> >> Bob
> >> =====================================> >> Bob Friesenhahn
> >> bfriesen at simple.dallas.tx.us,
http://www.simplesystems.org/users/bfriesen/
> >> GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/
> >>
> >> _______________________________________________
> >> zfs-discuss mailing list
> >> zfs-discuss at opensolaris.org
> >> http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
> >>
> >>
> >
> _______________________________________________
> zfs-discuss mailing list
> zfs-discuss at opensolaris.org
> http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
-- 
Adam Leventhal, Fishworks                     http://blogs.sun.com/ahl