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Re: Anyone using a SAN?

From: "Peter Koczan" <pjkoczan(at)gmail(dot)com>
To: pgsql-performance <pgsql-performance(at)postgresql(dot)org>
Subject: Re: Anyone using a SAN?
Date: 2008-03-14 21:09:36
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-performance
Hi all,

I had a few meetings with SAN vendors and I thought I'd give you some
follow-up on points of potential interest.

- Dell/EMC
The representative was like the Dell dude grown up. The sales pitch
mentioned "price point" about twenty times (to the point where it was
annoying), and the pitch ultimately boiled down to "Dude, you're
getting a SAN." My apologies in advance to bringing back repressed
memories of the Dell dude. As far as technical stuff goes, it's about
what you'd expect from a low-level SAN. The cost for a SAN was in the
$2-3 per GB range if you went with the cheap option...not terrible,
but not great either, especially since you'd have to buy lots of GB.
Performance numbers weren't bad, but they weren't great either.

- 3par
The sales pitch was more focused on technical aspects and only
mentioned "price point" twice...which is a win in my books, at least
compared to Dell. Their real place to shine was in the technical
aspect. Whereas Dell just wanted to sell you a storage system that you
put on a network, 3par wanted to sell you a storage system
specifically designed for a network, and change the very way you think
about storage. They had a bunch of cool management concepts, and very
advanced failover, power outage, and backup techniques and tools.
Performance wasn't shabby, either, for instance a RAID 5 set could get
about 90% the IOPS and transfer rate that a RAID 10 set could. How
exactly this compares to DAS they didn't say. The main stumbling block
with 3par is price. While they didn't give any specific numbers, best
estimates put a SAN in the $5-7 per GB range. The extra features just
might be worth it though.

- Lefthand
This is going to be an upcoming meeting, so I don't have as good of an
opinion. Looking at their website, they seem more to the Dell end in
terms of price and functionality. I'll keep you in touch as I have
more info. They seem good for entry-level SANs, though.

Luckily, almost everything here works with Linux (at least the major
distros), including the management tools, in case people were worried
about that. One of the key points to consider going forward is that
the competition of iSCSI and Fibre Channel techs will likely bring
price down in the future. While SANs are certainly more expensive than
their DAS counterparts, the gap appears to be closing.

However, to paraphrase a discussion between a few of my co-workers,
you can buy toilet paper or kitty litter in huge quantities because
you know you'll eventually use it...and it doesn't change in
performance or basic functionality. Storage is just something that you
don't always want to buy a lot of in one go. It will get bigger, and
cheaper, and probably faster in a relatively short amount of time. The
other thing is that you can't really get a small SAN. The minimum is
usually in the multiple TB range (and usually >10 TB). I'd love to be
able to put together a proof of concept and a test using 3par's
technology and commodity 80GB slow disks, but I really can't. You're
stuck with going all-in right away, and enough people have had
problems being married to specific techs or vendors that it's really
hard to break that uneasiness.

Thanks for reading, hopefully you found it slightly informative.


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