Data Storage - HP EVA6000 vs DS4700

Author

HP EVA6000 vs DS4700

apples

2006-12-06, 1:17 pm

I'm looking for some comments/feedback on the EVA6000 versus the
DS4700. I've read the specifications and gotten the pitch from each
vendor and personally I don't see that much difference between them.

As well, we're probably going to be connecting an IBM p550Q to the
storage and use VIO for a number of LPAR's. That fact tends to sway me
towards the IBM storage but I'm interested in hearing other people's
experiences - especially as it applies to AIX and VIO.

jls

2006-12-07, 1:14 pm

On 6 Dec 2006 08:14:02 -0800, "apples" <mar35ca@gmail.com> wrote:

>
>I'm looking for some comments/feedback on the EVA6000 versus the
>DS4700. I've read the specifications and gotten the pitch from each
>vendor and personally I don't see that much difference between them.
>
>As well, we're probably going to be connecting an IBM p550Q to the
>storage and use VIO for a number of LPAR's. That fact tends to sway me
>towards the IBM storage but I'm interested in hearing other people's
>experiences - especially as it applies to AIX and VIO.

I can't speak for the DS4700, but I do know a bit about the EVA.
The main benefit for EVA-series storage arrays is simplicity of
management.

Bus-based arrays limit the number of spindles you can have in a given
LUN in order to provide proper data protection due to hardware failure
(e.g., loss of a SCSI bus shouldn't take out the entire RAIDset). The
result is that the workload is spread across only a few spindles,
which means that it can degrade much more quickly. That requires you
to create more RAIDsets and more LUNs, and manually partition your
data across all of them (which can also complicate good backups).

EVAs are not so much bus-based, like SCSI. The EVA uses fibre drives,
and allows you to add lots of disks to "groups", which are then carved
up into LUNs to present to hosts. Big benefit is that performance is
spread out for all LUNs across a large number of spindles, giving very
linear degredation in performance. This allows you to keep your LUN
sizes larger. And, assuning you still have room in your cabinetry, if
performance does start to degrade, you can very simply add more
spindles, and then add them to the group. The EVA will normalize the
data for you in the background, and your workload will be spread
across additional disks: near instant improvement with no downtime.

The web-based management interface is very, very simple to use... and
there's also a scripting tool if you want to automate some tasks.

I have many painful memories of lots of unpaid overtime managing disk
space and performance among lots of disks/LUNs in the past. While I
don't do that work anymore on a day-to-day basis, I can definitely see
how a "virtualized" array, such as the EVA, would have made my life
much easier.

Guy Dawson

2006-12-08, 1:12 pm

jls wrote:

> I can't speak for the DS4700, but I do know a bit about the EVA.
> The main benefit for EVA-series storage arrays is simplicity of
> management.

Conversely, I can't speak for the EVAs but can say a little about
the DS4700.

We've just bought our first SAN (EMC CX300) and also looked at the
IBM DS4700 and the Hitachi AMS200.

Like the EVAs, the CX300, DS4700 and AMS200 are fibre channel devices.
They can support multiple, redundant links to the hosts (via a SAN
switch if desired) and use fibre channel disks. Each unit can have
two controllers (why would you not?) and both controllers are linked
to every drive. FC drives actually have two controller interfaces
on them so they can be connected to two controllers at the same
time. Typically, each drive is only accessed by one controller unless
the controller fails in which case control moves to the remaining
controller.

As we did not buy the DS4700 I can't say much in detail about its
software.

Guy
-- --------------------------------------------------------------------
Guy Dawson I.T. Manager Crossflight Ltd
gnues@crossflight.co.uk