Equallogic PS400E Usable Space?

[CoreyIT]

Hi All,

The PS400E is 10.5TB raw. Running a RAID-10 array on this any idea what the usable space is? Im guessing about 7.5 or so? Hopefully more but I thought I would ask in case someone had first hand experience.

Thanks

[acr]

Correct RAW is 10.5Tb as it use's 14 750G Disks.

RAID 10 useable is 4297.63TB[/b] and with RAID 50 its 7163.45TB[/b] then with RAID 5 youd get 8596.89TB[/b]

As with any Storage Array you'll loose the most to the RAID with RAID 10..

[scott_k]

I would go raid50

[CoreyIT]

Since its virtual storage in the sense that the entire array uses a single raid set what is the recommended array configuration? Raid 5 I dont think would be the best without having a spare hard drive on standby and to have that much data and systems relying on only a SINGLE drive failure I would be apprehensive about using raid-5 for such volume. Raid 50 on the other hand would allow you to utilize more space but at the cost of what performance vs. the raid10 config?

Anyone care to comment or share their experiences here?

[BUGCHK]

RAID-10 stores all data twice, so the best you could get is 50% of 10.5TB, but you should also think about spare disks which reduces the capacity further.

[acr]

The answer really lies in how much you are prepared to sacrifice, RAID10 is the better but the trade off is you loose the most.. RAID50 is or can be an acceptable alternative..

Ive seen no performance isses with RAID50..

[christianZ]

Agreed. Raid 50 should be the "gold choice" - don't forget you can configure only 2 spares or none.

[woharrow]

Why not use both?

If you were to take a PS-300E and run RAID 50 you would get 4.4TB of usable space. Then you add to that a PS-100E running RAID 10 which is 1.33TB of usable Space and you can have the best of both worlds

EqualLogic gives you the ability to have both RAID levels running in the same pool so that it appears to be one big space. The benefit is that the system will look at the host I/O for the volume on a 9 to 14 day window and determine which RAID level is best suited for the volume. Or you can over-ride that and preference a volume to one RAID type or the other.

Just as you can create a Quality of Service for VMs by running Shares at the CPU level you can now do the same for Disk Volumes by either letting the system help you decide, or by selecting the QOS yourself. *the other option is to set the arrays up as different Pools and then just move the volume between them if you want to change the QOS rating for that Volume. (and Yes this is done HOT just like VMotion)

If you don't mind spending a little bit more you can get a PS-3800XV which has the 146GB 15K SAS drives and use that for RAID 10 instead of the PS-100E I mentioned earlier. Now that's for people who have a few applications that need some screaming performance.

Hope this helps

Wade