SAN choice: EMC AX4-5 or Dot Hill 5730 (FSC FibreCAT SX100, Snapstor 5000, HP MSA2...fc?)

[Yabbadabbadu]

Hi,

we're planning a VMware vSphere environment and we're looking for a decent SAN for

about 80-90 VM's (most of them are test systems with low IOPS...)

We want to start with dual SP SAN devices, 4GB FC, 24x 450GB 15k SAS, redundant FC switches,

3 ESX servers (Fujitsu RX300S4 / 32GB / Dual Quad-Core XEON). Somewat later a second SAN

for backup will follow (SATA disks)

After a lot of researching, we want to decide between the remaining two candidates:

EMC AX-4 and Dot Hill 5730, because they fit into the buget (both cost the same...)

IMHO the pros/cons are:

Dot Hill pros:

- Cache-Backup with capacitor and flash

- Supports also Raid 50, 60

- All disks can be used for building Raid sets

- Supports more disk shelves / disks

- 4 instead of 2 FC ports per SP

Dot Hill cons:

- Replication or copy to a second san not possible

EMC pros:

- A lot of dokumentation

- CLI tools for scripting

- Many software options (SAN copy, Replication,...)

- Support for metaLUN

- more widely used / better support (?)

EMC cons:

- Software options very expensive

- The first four disks not freely usable becaus of the operating system (Windows XP + FLARE?)

- Batteries for cache backup (life time?)

The planned disk Layout was:

Raid 10 with 2x 4 disks for VMs with lot of random writes

Raid 50 with 3 times 4+1 disk for all other VMs

One global hot spare

But with EMC, this layout is not possible because of the 4 system disks with a fixed layout.

With the EMC we can only do some Raid 5 sets and striped metaLUNs for a little bit more

performance...

At this time, it looks like we'll never use SAN copy or replication, because we want

to use a VMware backup solution. So it's very difficult to make a decision...

Anyone who has experience with one of the systems or both systems?

Performance, reliability, usability...

Or any comments on the disk layout?

Thanks for the Help!

[AndreTheGiant]

about 80-90 VM's (most of them are test systems with low IOPS...)

You say low IOPS but are a lot of VM.

You may need 4 or 5 different LUN (possible on distinct RAID group).

And what about the disk space that you needed?

I do not know "Dot Hill 5730", but I know AX.

If you think to scale up with other disks, then could not be the best solution.

Andre

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[KellyOlivier]

I love DotHill products. I have used several 2730s in different builds. You CAN script with these. They have pl modules. Their GUI is really easy, but you can also use command line. Are you sure they don't have replication between SANs? I remember them telling me that it was in the roadmap.

[Lightbulb]

Cant say anything for/against the Dot Hill stuff but have worked with EMC and overall their systems work well. The cli is anoyingly non-intuitive (Compared to 3PAR which has the easiest provisioning I have ever come across, but I would guess outside of your budget.

As far as support the "EMC" company support can be hit or miss but Powerlink (Their online support resource) is quite good and there are some pretty sharp folks in the forums.

80-90 VMs is a fairly large number but if they are low I/O you can get about 20-25 to a datastore so either SAN should allow for the space. IIRC correctly the AX has max of 60 disks but with only 2 controllers I would only think of provisioning about half that (The rest would be used for snaps but you arent going to be doing that)

Also again IIRC the AX will not easily scale into a bigger EMC SAN (CX etc etc) so bear that in mind.

[Yabbadabbadu]

> You say low IOPS but are a lot of VM.

> You may need 4 or 5 different LUN (possible on distinct RAID group).

Is it better to define distinct RAID groups? I thought for performance and flexibilty it would

be better to define 2 bigger RAID groups (10 or 50), one group for each SP....

With the AX we wanted to define a number of RAID 5 groups and use the metaLUN with

striping. (They don't support Raid 50...)

And I planned to use more small LUNs (300 - 600GB each, max. 8 VMs per LUN)

> And what about the disk space that you needed?

I'd be very happy with 7TB and happy with 6TB (I calculated 5TB diskspace)

> I do not know "Dot Hill 5730", but I know AX.

> If you think to scale up with other disks, then could not be the best solution.

The maximum will be one additional DAE with 12 disks within the next few years. Doesn't the AX scale up well?

[AndreTheGiant]

Is it better to define distinct RAID groups?

If possible yes, you have different disks so are you sure that I/O operation are separated.

I'd be very happy with 7TB and happy with 6TB (I calculated 5TB diskspace)

In this case have a look also at some hi-level iSCSI solutions.

I know Equallogic and probably the cost will be similar.

Andre

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