# Poundhost Data Storage

The dedicated server which this website and all my other personal stuff runs on
is hosted with [PoundHost.com](http://www.poundhost.com/). They're cheap, offer
very good technical support, and have been generally reliable for the several
years I've used them. They recently started offering a service called [Data
Storage](http://www.poundhost.com/storage/). You can basically rent storage
space by the gigabyte, and they'll make it accessible to you via iSCSI. So if
you have a dedicated server or colocated machine with them, you can mount that
storage on it.

It's cheap too. 17 pence per gigabyte for the cheapest option, and there are no
per/bandwidth or per/IO charges like you'd receive with [Amazons EC2
services](https://aws.amazon.com/ec2/)
([S3](https://aws.amazon.com/s3/)/[EBS](https://aws.amazon.com/ebs/)).

I started playing with it recently because I wanted to be able to share a
filesystem between multiple servers for redundancy. I've used 100% free
software. Specifically, I've been using [Redhat Cluster
Suite](https://www.redhat.com/cluster_suite/) on a pair of
[Centos](https://centos.org/) 5.3 <abbr title="Virtual Machines">VMs</abbr>
running on top of [VMWare server](https://www.wikipedia.org/wiki/VMware_Server),
clustered <abbr title="Logical Volume Manager">LVM</abbr>, and
[GFS](https://www.wikipedia.org/wiki/GFS2). They use a [HP LeftHand
SAN](http://www.compaq.com/storage/highlights/lefthandsans.html), which supports
SCSI reservations which means you can do proper automated
[Fencing](https://www.wikipedia.org/wiki/Fencing_%28computing%29) too.

All in all, it's quite a neat solution. There are drawbacks though. Poundhost
Dedicated Servers come with 100Mb <abbr title="Network Interface
Cards">NICs</abbr>, which means you're limited to a theoretical maximum of 12.5
megabytes per second to read/write from/to it. In practice, I get about 8
megabytes per second. I know this because I've been running
[hdparm](https://www.wikipedia.org/wiki/Hdparm) against the device once every
ten minutes for several days now and logging the results. Of course, I'm sharing
the storage network and disks with other people, so my performance is going to
be dictated by the behaviour of other users.

You can choose to pay twice as much per gigabyte for "two-way replicated"
storage, and apparently it's straight forward to change from one to the other.
If you get two-way replicated storage then it has a 100% SLA, and any downtime
means you get your full monthly cost refunded. I don't have two-way replicated
though, which means I get **NO SLA**. I didn't realise this until yesterday. The
storage stopped responding at about 11:30 in the morning, and it took them about
four hours to get it back online. From following the status page, most of that
time seemed to be in getting the HP engineer on site. That's the trouble when
you buy a proprietary solution, you can't always fix it yourself. I'm not sure
if it affected the two-way replicated storage, but it certainly affected mine.

I'm going to keep using it and monitoring its performance and uptime. It's
useful for backing up data, but I don't currently trust it enough to run a live
platform off it. Poundhost themselves obviously do, as they run their VPSs off
it, so I expect downtime like this to be a rare thing.