2009/11/13 Greg Smith g...@2ndquadrant.com:
In order for a drive to work reliably for database use such as for
PostgreSQL, it cannot have a volatile write cache. You either need a write
cache with a battery backup (and a UPS doesn't count), or to turn the cache
off. The SSD performance
Greg Smith wrote:
Karl Denninger wrote:
With the write cache off on these disks they still are huge wins for
very-heavy-read applications, which many are.
Very read-heavy applications would do better to buy a ton of RAM
instead and just make sure they populate from permanent media (say by
Itching to jump in here :-)
There are a lot of things to trade off when choosing storage for a
database: performance for different parts of the workload,
reliability, performance in degraded mode (when a disk dies), backup
methodologies, etc. ... the mistake many people make is to overlook
the
-Mensaje original-
Laszlo Nagy
My question is about the last option. Are there any good RAID
cards that are optimized (or can be optimized) for SSD
drives? Do any of you have experience in using many cheaper
SSD drives? Is it a bad idea?
Thank you,
Laszlo
Never
Brad Nicholson wrote:
Out of curiosity, what are those narrow use cases where you think
SSD's are the correct technology?
Dave Crooke did a good summary already, I see things like this:
* You need to have a read-heavy app that's bigger than RAM, but not too
big so it can still fit on SSD
*
2009/11/13 Greg Smith g...@2ndquadrant.com:
As far as what real-world apps have that profile, I like SSDs for small to
medium web applications that have to be responsive, where the user shows up
and wants their randomly distributed and uncached data with minimal latency.
SSDs can also be used
Fernando Hevia wrote:
Shouldn't their write performance be more than a trade-off for fsync?
Not if you have sequential writes that are regularly fsync'd--which is
exactly how the WAL writes things out in PostgreSQL. I think there's a
potential for SSD to reach a point where they can give
The FusionIO products are a little different. They are card based vs trying to
emulate a traditional disk. In terms of volatility, they have an on-board
capacitor that allows power to be supplied until all writes drain. They do not
have a cache in front of them like a disk-type SSD might.
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