 | | | RHEL + SAN feedback | RHEL + SAN feedback 2005-06-27 - By Tom Sightler
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On Mon, 2005-06-27 at 12:38 -0700, Tobias Speckbacher wrote:
For the last 2 years I've been the owner of three CX400's and can tell
you a little about my experience. In a nutshell, I think the systems
are great, and very flexible, but they do have certain "issues" when
used with Linux, mainly EMC's required to use PowerPath (a binary
module) to provide multipath. I wrote a little more detail about that
in another email.
> My main criteria are in order of importance:
>
> 1. Management
I've found that managing my CX400's is quite simple. They provide a
Java based interface that runs well on both Windows and Linux and
provides a pretty intuitive interface. They also provide excellent
command line tools which allow for scripts to be written to automate
tasks. Pretty much anything you can do with the GUI you can do with the
command line, and for the most part it works the other way as well.
Our three arrays are located in multiple physical sites but all are
managed via a central console and this works well, although a little
slow sometimes. In general I would say management is a breeze.
> 2. Scalability
Overall the system is quite easy to expand and we've had no real issues
increasing the number of connected hosts, adding additional storage, or
implementing new features. We've performed non-disruptive upgrades to
new code releases without interrupting service.
We did recently decide to upgrade our primary array to a CX700 simply to
get the higher FC port count in the back of the unit, as we were
starting to see some saturation of the backend links during our peak
periods, but overall the whole head unit seems well sized and balanced
between front-end port count and back-end connectivity.
> 3. Support
Overall, EMC support has been great, although we did have one major
failure that occurred on the weekend and it took the 14 hours to
escalate the issue to a level high enough to even understand the
problem. Our systems were not down during this time, but we were
running non-redundant for that period of time. It turned out to be a
software issue in the code running on the Clariion and once they finally
escalated to the proper group it was repaired quickly.
Actually, almost every problem we've had has been a code problem, but
recent code versions seem to have most of the issues ironed out. Most
of the were minor annoyances, things like the management agent hanging
or responding slowly, but they were still annoying.
> 4. Performance
We've found the performance to be very close to what is advertised, and
possibly better. Our previous storage vendor seemed to advertise a rate
which was not achievable in the real world, especially for the write
performance, however, we were easily able to push or CX400's higher than
EMC's published rates, and while we did have to do a little tuning, we
managed sustained sequential read and write performance that was near
the saturation point for the available backend bandwidth. That's about
all you can expect from an array.
Anyway, these are just my thoughts. I don't think EMC is a bad choice,
but their strict reliance on PowerPath, which can be relatively pricey,
is what I would consider their biggest negative, but it's pretty big.
Once the disk mapper EMC support in RHEL4 is more proven then this may
not be as big of a deal.
Later,
Tom
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