EMC AX4 SATA vs HP DL380 WSS SAS 15k

[Gihzmo]

I am hoping someone has some experience with both of these systems, or comparable systems. We are currently running an HP DL380 Windows Storage Server with 8 300GB 15k SAS Drives. This is supporting four VMware ESX hosts running about 40 VMs.

We are looking at buying an EMC AX4 with 8+1 SATA drives. I am curious to know how much of a performance decrease we will be looking at moving from 15k SAS drives to SATA drives. I am alson wondering how much a difference the EMC cache and dedicated storage OS will make versus a Windows storage server serving up virtual iSCSI LUNs.

I know overall that the EMC is a much better system, but I am concerned about moving to SATA drives and seeing a performance decrease.

We are also going to be adding 2 XenServer hosts to this storage array for supporting XenDesktop virtual desktops primarily.

 

[mrdenny]

SATA disks are create if they will only be doing one, maybe two things at a time. Once you get more than that performance will degrade quite a bit. The AX4 should support SAS drives, granted they are more expensive than the SATA, but they are quite a bit faster.

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[xmsre]

A 7200 RPM SATA drive is only capable of about 40 random IOs at a 20ms response time.

A 15K SAS drive can do 180ish.

RAID 5 (idependent of the platform) has a write penalty of 4. It's suited for applications that read far more than tey write. RAID 10 has a write penalty of 2, and is better suited to applications that have a higher percentage of writes.

I'd look at your current environment, take some measurements, then figure out what the performance you need is. Then you can make an informed decision about disk and RAID type.