RE: Solid State Drives

  • From: "Matthew Zito" <mzito@xxxxxxxxxxx>
  • To: <andrew.kerber@xxxxxxxxx>, <dofreeman@xxxxxxxxxxx>
  • Date: Fri, 1 May 2009 10:47:05 -0400

Bear in mind that enterprise SSDs are already write-leveled at a
hardware level.  The big optimization for filesystems with enterprise
SSD is making sure that filesystem blocks are aligned with the same
block structure as the SSD is using - for cheap SSDs that don't do write
leveling, then there's a lot of CoW optimizations you can do. And you
would still RAID your disks - write leveling is nice, but it doesn't
handle the failure of a controller chip or something similar.  So you're
never going to get away from that.  As far as the upgrade path, the
lifespan is comparable for a "spinning rust" hard drive.






From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Andrew Kerber
Sent: Friday, May 01, 2009 10:18 AM
To: dofreeman@xxxxxxxxxxx
Cc: Oracle-L (oracle-l@xxxxxxxxxxxxx)
Subject: Re: Solid State Drives


I wrote an article in IOUG Select journal about Solid State.  I really
think Solid Statie is the coming thing.  At this point, it is too
expensive to put all your storage on SS, but if you put your popular
tables on it, you can see substantial speed improvements.

If they can resolve the write issue, I could see SS really helping to
reduce pinging in RAC by making the IO to disk almost as fast as the IO
to cache, thus reducing the required cache sizes and the pinging caused
by that.  Redo log would also be a good usage for SS, reducing the time
to switch logs.

Currently, the developers are centered on leveling the writing, that is
making the level of writes the same across all portions of the SSD.
That is showing promise in extending the life of the SS storage.
Solaris is working on a major initiative in SSD, I dont know how that
will be affected by their purchase by Oracle

On Fri, May 1, 2009 at 9:09 AM, Freeman, Donald <dofreeman@xxxxxxxxxxx>

Has anybody given any thought to where we are going as SSD's get cheaper
and bigger?   We've been going round and round at my shop with
discussions about RAID, other disk allocation issues, fights over
storage.  I mean we seem to spend a lot of time on that issue. I saw
that IBM is testing a 4 TB SSD.   I was wondering if you'd have to
mirror that, What kind of reliability we would be getting.   No more
RAID discussions?   I've heard there is a finite number of times you can
write to it.  What's the upgrade path here?

Andrew W. Kerber

'If at first you dont succeed, dont take up skydiving.'

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