RAID 1 or RAID 5

[hfourie]

Just a quick Q here. Im setting up some ESX servers on HP DL360 G% servers. Is it better to have 2 SAS disks internally for ESX RAID 1 or rather 3 x SAS with RAID 5.

Im leaning towards RAID 5, but what do you think?

[admin]

There's not really any advantage to having ESX installed on RAID 5 rather than RAID 1, so I'd save the cost of the extra disk and go with a RAID 1 install.

However, if you're putting a VMFS volume on these disks - probably better to go with the RAID 5.

[VirtualNoitall · Accepted solution]

Hello,

If the disks are for ESX, and not VMFS, then stick with RAID 1. For your VMFS file system, if it will be on the remaining 4 drives, go RAID 10 if you can afford to give up the space as write performance will be better. If you need the disk space you would get from RAID5 then go that way but a BBWC, as mentioned below, is a must to compensate for reduced write performance.

I would recommend, which ever way you go, you look at a battery backed write cache so you can enable a write cache. We noticed a very large performance gain on our DL360 G5s after enabling write cache.

[tor_s_eilertsen]

Hi

If you have 3 disks available, and you plan not to have any VMFS locally, the most redundant configuration would be RAID1(mirror) + hotspare!

This gives a 66% overhead, but if you don't need the space and if the disks are already there, use them!

[whynotq]

it will depend on what you purchase on the server side.

If you are using shared storage then I'd keep it to a pair and mirror them then spend the extra $ on memory.

if you are using the internal storage for a VMFS then I'd try to get 5 disks and have a mirror for the ESX install and a R5 2+1 for the vmfs.

[hfourie]

Thanks for all the feedback. I will only put esx on the internal disks. VMFS will sit on the SAN.

Think I will use the £££ saved from getting only 2 disks / server in stead of 3 and get that BBWC.

Thanks

[VirtualNoitall]

Happy to help!

If you are only using the internal disks for ESX itself, and not hosting VMFS partitions, then you might not get the value from the BBWC.

[hfourie]

Thanks for that. Might invest the extra ££ somewhere ele.

[fochmat]

Any sugestions about Stripe Size ? May I get more performance for different Stripe size ?

Thanks

[fox1977]

What setup did you end up going with?

Looking at the same thing myself. Looking at raid 1 with spare for ESX partition and 3 x 500gb to store vmfs locally. Stuck between raid 1 and raid 5. All a question of performance. I'm tempted to go with raid 5 for vmfs based on people's comments on here.

[hfourie]

I ended up having mirror disks internal to esx servers, and all vmfs datastores on SAN. Works well. Didnt bother having hot spare for esx hosts, as HP agents will tell me when one is about to fail, and HA etc should take care of things if all goes horribly wrong.