RE: Flash technology based HDD will it make significant difference for OLTP applications?
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.
[mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Niall Litchfield Sent: Monday, January 07, 2008 4:29 PM
Subject: Re: Flash technology based HDD will it make significant difference for OLTP applications?
Things I don't like about it.
- It's end of life and the manufacturer is recommending other products from a different product line.
- 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
- you are IO bound and
- 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.
NiallReceived on Tue Jan 08 2008 - 10:12:12 CST