RE: Flash technology based HDD will it make significant difference for OLTP applications?
- From: "Matthew Zito" <mzito@xxxxxxxxxxx>
- To: <niall.litchfield@xxxxxxxxx>, <j.velikanovs@xxxxxxxxx>
- Date: Tue, 8 Jan 2008 11:12:12 -0500
I'm fairly neutral on the subject of RAM-and-SSD storage technologies,
as I think far more improvements would be had overall by tuning queries
and applications correctly, instead of trying to optimize the storage.
However, one technical point - all of the SSD technologies to
write-balancing, to make sure that blocks get written to evenly over
time, as well as detecting failing blocks and moving their data over to
good ones. With flash or other SSD storage, a "block" is just a logical
mapping to an arbitrary point on the flash memory, since there's no
rotational performance impact.
Thanks,
Matt
________________________________
From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Niall Litchfield
Sent: Monday, January 07, 2008 4:29 PM
To: j.velikanovs@xxxxxxxxx
Cc: oracle-l
Subject: Re: Flash technology based HDD will it make significant
difference for OLTP applications?
Things I don't like about it.
1. It's end of life and the manufacturer is recommending other products
from a different product line.
2. I really don't like the idea of a san disk expiring after x I/O
operations - I don't know how many i/os my disks have been subjected to,
or are subjected to on a regular basis, and what the variation is. I've
not yet met anyone who does either - though I have a sneaking suspicion
that I might know at least one person who does keep this info.
then there's the broader question as to whether
a) you are IO bound and
b) the IO that is binding you is optimised.
Of course redo IO is optimised and often is a significant drain so SSD
devices might be approprate there.
Niall
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