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Re: SSDs and the Reliability Factor



fixed

Should they fail? No. But anything manufactured can be defective, including
memory. Hopefully truly defective components would be revealed in the QC
process. And in a server you will still be installing them as part of a RAID
set; the need for that does not go away.

BTW, like platter drives SSDs have more space than advertised. So there is
some room to remap around bad or defective memory sectors just like platter
drives do with defective disk sectors.

It's been estimated that the average MLC SSD can be written to 24x7
(continuously) for 5 years before you're likely to start to see problems.
Reads are unlimited; only writes add to the wear.

On Tue, Sep 29, 2009 at 3:05 PM, ibm <ibm@xxxxxxxxxx> wrote:

What about defective SSDs? Should they fail within the first few hours
of operation as mechanical drives 'do'?

http://www.tomshardware.com/reviews/Intel-x25-m-SSD,2012-5.html

-----Original Message-----
From: midrange-l-bounces@xxxxxxxxxxxx
[mailto:midrange-l-bounces@xxxxxxxxxxxx] On Behalf Of John Jones
Sent: Tuesday, September 29, 2009 2:31 PM
To: Midrange Systems Technical Discussion
Subject: Re: SSDs and the Reliability Factor

That article really wasn't very informative. For instance, the author
didn't mention that MLC SSDs are good for roughly 10K write cycles
before
any reliability degradation should occur and 100K write cycles for SLC
disks. No mention of wear leveling or the forthcoming TRIM
implementation
which stabilizes performance levels.

Calling SSDs no better than platter-based drives is only correct when
comparing prices & storage density. For those factors, platter drives
are
better. But SSDs draw less power, generate less heat, and the good ones
will run circles around platter-based drives when it comes to IOs/second
and
sustained transfer rate. For reliability, SSDs can last just as long as
their spinning brethren. They are less likely to have random failures
and
are immune from head crashes since there are no heads.

If you have time and want a more technical dive, check out what Anand
has
written. The latest is at
http://www.anandtech.com/storage/showdoc.aspx?i=3631 and it links to the
first article in the first paragraph. Granted, Anand's site is geared
towards the PC enthusiast but the technical details are just as relevant
for
a server implementation (x86 or Power).


On Tue, Sep 29, 2009 at 1:08 PM, Chuck Lewis
<chuck.lewis@xxxxxxxxxxxxxxxxx>wrote:

With the talk of SSD's today this was timely:

http://tinyurl.com/y9j2ztz

Chuck
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--
JJ
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- Homer J. Simpson
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