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part of a long running series of articles -
Are MLC SSDs
Safe in Enterprise Apps? |
Editor:- December 7, 2010 -
Fusion-io
today announced that it has been
working closely with Credit
Suisse to integrate ioMemory SSDs with its
Advanced
Execution Services trading platform to improve its data access performance,
maximizing the effectiveness of its low latency trading platform architectures.
Editor's comments:- trading banks using SSDs isn't new. So my initial
inclination was to ignore this news story. But I'm glad I didn't - because I
learned a lot when I spoke to Fusion-io's CEO
David Flynn yesterday.
I
asked David Flynn - what's your feedback from banks and financial customers
about the issue of MLC versus SLC (SSDs) in their critical financial apps. Is
it something which they say they have concerns about?
David Flynn's
answers surprised me and I hope you find them interesting too.
Re
MLC vs SLC
concerns in Fusion-io's financial customer base...
David said
that their customers don't raise this as a concern. Over 80% of the SSDs
that Fusion-io has sold in the last couple of years have been MLC rather than
SLC - and he thinks that they probably have a bigger base of enterprise MLC SSDs
which has been operating longer in customer sites (upto 3 years) than any other
company.
David Flynn said that while MLC poses technical challenges
Fusion-io's flash management architecture (some of which I have
written about
before) provides high data integrity. For example - their SSDs don't lose
any data even if entire flash chips fail. That in itself isn't unique - but
something new to me was learning that their SSDs do data healing (just
like some of the high end RAM
SSDs).
He said that - in additional to real-time data integrity
checks - their SSDs do a weekly background read, verify, fix and rewrite
of the entire flash array to prevent
bit rot.
(Data can get corrupted in seldom used flash blocks due to charge leakage as
well as disturb errors
due to other write activities in the same chip. The data healing process ensures
that users don't have to over rely on the long term data retention
characteristics of the raw flash.)
I asked David Flynn what his view
was about data
recovery of flash SSDs. He confirmed my guess that most enterprise
customers don't need it - because they're doing backups. He also said he
didn't recall any cases where their own SSDs had suffered from
endurance
related burnout.
While on this subject we talked about the advantage
of SSD accelerated backup.
He said that a general problem for high work load customers using just hard
disk storage was that they couldn't extract data in real-time to do backups
because their user application performance would suffer. |
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David Flynn said that a beneficial side
effect for many customers who used their SSDs was that they could do
backups about 6x
faster and for many customers it was viable to do backups while their servers
were at peak user loads. | | |
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