6 local Disk Layout question.

[eos11]

We have a big server (R815) with 128GB ram and 32 cores for a staging environtment (so performance and relability are nice to have, but not critical)  It will house about 20 servers including a bunch of mysql dbs and a mssqlserver db.

It has 6x900GB SAS drives internally on a Perc h700 controller.

The box arrived with one big RAID 5 array, with 3 Virtual disks:

1: 500GB

2: 1.8TB

3: 1.8TB.

We could just install vsphere on 1, and use 2 and 3 for VMs.

However, we expect 500GB is too much.  How much should be reserved to install vSphere 5 and run it for years?  We have seem some posts saying 5GB, some saying 10GB, and some saying 100GB.

Many people recomend raid 10 (i.e. 3 stripes of middored disks), but this reduces the storage from about 4.5TB to 2.7TB, which may be too small.

Some people suggest raid 6, but this reduceds our capacity from about 4.5TB to 3.6 for a reliability inrease we dont care too much about, and a potential performance drop (some people say raid 5 is faster, some say its slower, some say it depends on the controler).

We undestand the advantage of keeping the VM partitions to less than 2TB.

Suggestions?

[arturka]

Hi

I would install ESXi5 on USB.

Regarding disk layout, if you don't need resiliency at all, create 3 x RAID0 - the best performance but zero redundancy 🙂

Create one VMFS per LUN or spread one VMFS across 3 LUNs.

read that before

http://www.yellow-bricks.com/2009/12/23/iops/

Artur

[a_p_]

Personally I think with the requirements you mentioned the RAID 5 with 6 disks is the way to go. The virtual disks were most likely setup this way to support ESXi 4.x. With ESXi 4.x logical volumes (virtual disks) are limited to 2TB minus 512 bytes, ESXi 5.0 allows 64TB.

We have seem some posts saying 5GB, some saying 10GB, and some saying 100GB.

ESXi will install on 1GB and create a scratch partition of 4GB (unless installed on USB). Since some vendors calculate the disk sizes in decimal values (e.g. 5GB = 5,000 MB instead of 5,120MB), a 5GB virtual disk may just be a little bit too small. That's why the minimum size should be 6GB. I usually allow 10GB to make sure there's some spare space in case it's needed some time in the future. The reason to use a separate virtual disk was based on the fact that a reinstallation of ESXi 4 wiped the whole disk. With ESXi 5.0 there's an option to preserve the VMFS partition.

With ESXi 5.0 you have all options for the disk configuration. You could go with one large virtual disk or split the RAID into several virtual disks. I'd probably go with a 10GB virtual disk for ESXi and 2 or 3 virtual disks for the VMFS volumes.

André