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From Ben Gambley <ben.gamb...@intoscience.com>
Subject Re: Cassandra with SAN
Date Fri, 22 Feb 2013 06:23:39 GMT
On Friday, February 22, 2013, Jared Biel wrote:

> > 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.
>
> This is certainly true when using EBS, however it's generally not
> recommended to use EBS when running Cassandra. EBS has proven to be
> unreliable in the past and it's a bit of a SPOF. Instead, it's recommended
> to use the "instance store" disks that come with most instances (handy
> chart here: http://www.ec2instances.info/). These are the rough
> equivalent of local disks (probably host level RAID 10 storage if I'd have
> to guess.)
>
> -Jared
>
> On 22 February 2013 00:40, Michael Morris <michael.m.morris@gmail.com>wrote:
>
> 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]
> *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" <
>
>

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