🚀 go-pugleaf

Penang schrieb:
> Please pardon me if this topic has been discussed before, but as far
> as I know about the Flash memory, they have a relatively low limit on
> re-write, as compared to hard disk
> 
> In situation where database use in concern, read and write operation
> takes place very often
> 
> I know that there are pros and cons in this issue, but basically my
> question is this --- How reliable is SSD?

Hi Penang,

sorry for joining in so late, but I did not have access to
usenet the last 4 days.

You will find a  l o t  of useful information at
www.storagesearch.com

To make it short:
A flash disk is not a real SSD.
Real SSDs do like 16K IOPS per disk
and they are very reliable, very expensive and
on the market for like 20+ years.

There are 2 types of flash disks: SLC (single layer) -
smaller (i.e.upto 64GB), more expensive and faster.
MLC (multi layer) - those are bigger (upto 512GB from
Toshiba) usually 256 GB now and in the EUR 600 price
range for 256 GB.

So if a flash disk 'wears out' first thing to happen is,
that is gets slower, much slower, that is, and in a
short period of time (exactly this is Intel's problem atm).

After a long period they finally are so slow, that I think
they might never die from wearing out .....
I am not that far in testing, though.

What I do in week 9 atm is trying to do harm to the
ones I testing. I give them 2800 IOPS writing only
and 2 KB blocks only. I have to types: internally
having 4 KB blocks or 8 KB blocks.
So I write 86400 x 2800 blocks per day for 64 days now.
None is slower that at the beginning - so far.

If you can throw in a lot of money, have a look
at the real speed: Texas Memory Systems
www.ramsan.com

Or on a much cheaper scale: the 12 slot boxes from
www.infortrend.com (in heavy use at CERN, Switzerland).

And  n e v e r e v e r  go RAID5 using a flash disk!
Writing the parity there kills a third of the lifetime.
www.baarf.com has all on RAID5 and why never it is a good
idea.

dic_k

-- 
Richard Kofler
SOLID STATE EDV
Dienstleistungen GmbH
Vienna/Austria/Europe