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From Michael Morris <michael.m.mor...@gmail.com>
Subject Re: Cassandra with SAN
Date Fri, 22 Feb 2013 00:40:14 GMT
I'm running a 27 node cassandra cluster on SAN without issue.  I will be
perfectly clear though, the hosts are multi-homed to different
switches/fabrics in the SAN, we have an _expensive_ EMC array, and other
than a datacenter-wide power outage, there's no SPOF for the SAN.  We use
it because it's there, and it's already a sunk cost.

I certainly would not go out of my way to purchase SAN infrastructure for a
C* cluster, it just doesn't make sense (for all the reasons others have
mentioned).  Any more, you can load up a single 2U server with multi-TB
worth of disk, so the aggregate storage capacity of your C* cluster could
potentially be as much as a SAN you would purchase (and a lot less hassle
too).

As a counter argument though, anyone running a C* cluster on the Amazon
cloud is going to be using SAN storage (or some kind of proprietary storage
array) at the lowest layers...Amazon isn't going to have a bunch of JBOD
running their cloud infrastructure.  However, they've invested in the
infrastructure to do it right.

- Mike

On Thu, Feb 21, 2013 at 6:08 PM, P. Taylor Goetz <ptgoetz@gmail.com> wrote:

> I shouldn't have used the word "spinning"... SSDs are a great option as
> well.
>
> I also agree with all the "expensive SPOF" points others have made.
>
> Sent from my iPhone
>
> On Feb 21, 2013, at 6:56 PM, "P. Taylor Goetz" <ptgoetz@gmail.com> wrote:
>
> Cassandra is designed to write and read data in a way that is optimized
> for physical spinning disks.
>
> Running C* on a SAN introduces a layer of abstraction that, at best
> negates those optimizations, and at worst introduces additional overhead.
>
> Sent from my iPhone
>
> On Feb 21, 2013, at 6:42 PM, Kanwar Sangha <kanwar@mavenir.com> wrote:
>
>  Ok. What would be the drawbacks J****
>
> ** **
>
> *From:* Michael Kjellman [mailto:mkjellman@barracuda.com<mkjellman@barracuda.com>]
>
> *Sent:* 21 February 2013 17:12
> *To:* user@cassandra.apache.org
> *Subject:* Re: Cassandra with SAN****
>
> ** **
>
> No, this is a really really bad idea and C* was not designed for this, in
> fact, it was designed so you don't need to have a large expensive SAN.****
>
> ** **
>
> Don't be tempted by the shiny expensive SAN. :)****
>
> ** **
>
> If money is no object instead throw SSD's in your nodes and run 10G
> between racks****
>
> ** **
>
> *From: *Kanwar Sangha <kanwar@mavenir.com>
> *Reply-To: *"user@cassandra.apache.org" <user@cassandra.apache.org>
> *Date: *Thursday, February 21, 2013 2:56 PM
> *To: *"user@cassandra.apache.org" <user@cassandra.apache.org>
> *Subject: *Cassandra with SAN****
>
> ** **
>
> Hi – Is it a good idea to use Cassandra with SAN ?  Say a SAN which
> provides me 8 Petabytes of storage. Would I not be I/O bound irrespective
> of the no of Cassandra machines and scaling by adding ****
>
> machines won’t help ?****
>
>  ****
>
> Thanks****
>
> Kanwar****
>
> ** **
>
> ----------------------------------
> Copy, by Barracuda, helps you store, protect, and share all your amazing
> things. Start today: www.copy.com <http://www.copy.com?a=em_footer>. ****
>
>   ­­  ****
>
>

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