Re: SSDs with Postgresql?

On 20/04/11 04:28, Yeb Havinga wrote:
> On 2011-04-19 19:07, Benjamin Smith wrote:
>>
>> On Sunday, April 17, 2011 01:55:02 AM Henry C. wrote:
>>
>> >
>>
>> > Exactly. Be aware of the risks, plan for failure and reap the rewards.
>>
>>
>> Just curious what your thoughts are with respect to buying SSDs and
>> mirroring them with software RAID 1. (I use Linux/CentOS)
>>
>
> Since SSD fail when the write cycles are gone, it wouldn't make sense to
> buy two identical ones and put them in a RAID 1: under normal
> circumstances they'd fail simultanously.

I don't think SSD drives wear out in quite the manner you seem to
describe. The wearing out of blocks is not something that occurs at an
exact number; the quoted amounts are more of an average, and will vary
from block to block and from drive to drive.

Also, all decent SSD drives will remap bad blocks as they wear out, so
you don't get just one and then die.

Also, the number of erase cycles you can get, over the whole disk, is
quite large on modern disks!

So large that you'll probably go decades before you wear the disk out,
even with continual writes.

Don't buy into the SSD FUD myths..

Cheers,
Toby