On Jan 23, 2008, at 2:57 PM, Guy Rouillier wrote:
Scott Marlowe wrote:
I assume you're talking about solid state drives? They have their
uses, but for most use cases, having plenty of RAM in your server
will
be a better way to spend your money. For certain high throughput,
relatively small databases (i.e. transactional work) the SSD can be
quite useful.
Unless somebody has changes some physics recently, I'm not
understanding the recent discussions of SSD in the general press.
Flash has a limited number of writes before it becomes unreliable.
On good quality consumer grade, that's about 300,000 writes, while
on industrial grade it's about 10 times that. That's fine for mp3
players and cameras; even professional photographers probably won't
rewrite the same spot on a flash card that many times in a
lifetime. But for database applications, 300,000 writes is
trivial. 3 million will go a lot longer, but in non-archival
applications, I imagine even that mark won't take but a year or two
to surpass.
Please let outdated numbers rest in peace.
http://www.storagesearch.com/ssdmyths-endurance.html
Conclusion:
"With current technologies write endurance is not a factor you should
be worrying about when deploying flash SSDs for server acceleration
applications - even in a university or other analytics intensive
environment. "
That said, postgresql is likely making assumptions about non-volatile
storage that will need to be shattered once SSDs become more widely
deployed. Perhaps SSDs will replace RAID BBUs and then the HDs
themselves?
Cheers,
M
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