22 Jan
2011
22 Jan
'11
2:50 p.m.
On 22 jan 2011, at 11:10, Mariano Martinez Peck wrote:
On Fri, Jan 21, 2011 at 5:12 PM, Tudor Girba
<tudor.girba(a)gmail.com> wrote:
Just a question: Would the new slate disks not alleviate the problem of the disk speed?
For Gemstone, Hernan Wilkinson did some test 1 o 2 years ago, and the difference
was....mmmm I dont remember, but I think 40x faster. All the Gemstone migrations and I
don't remember what more, was done with that HDD. So, yes, at least in Gemstone it
changes a lot.
Latency for reading is 65-75 microseconds. That is a lot better than hard disks. For
writing the situation is different. There SSDs can be comparable to a HD (up to a few
times faster) when having to clear a page. You'll only notice this after all pages of
the SSD have been written. Before that, performance will be spectacular. Documentation on
real (long term) write performance of SSDs is hard to get/interpret.
http://www.slideshare.net/matsunobu/ssd-deployment-strategies-for-mysql
And of course SSDs are still more than 100 times slower than ram.
Stephan