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I have a customer with the following set up, does it make sense...? A large VM machine, 64 GB with SAN

Then a sql server machine that has Partition C:\ on LUN with Raid 5 Partition D:\ on LUN with Raid 1

Both Partitions are in a Disk array of 10 discs, with Raid 10. In this disc array there are also other Maschines with Partitions on a LUN with Raid 5.

In total on the VM machine there are a total of 22 VMs running!!

My largest concern, other than there being soo many VMs running simultaneously is the redundant nature of Raid 5 in a raid 10 array etc. Is that normal??

Cheers alex

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Your description of how the logical volumes in the SQL server are built up is not clear. I think I understand what you mean and I've answered accordingly but a clearer description of how the RAID volumes in the SQL server are built would help, where the SQL VM's disks come from (VMDK\RAM) and how many LUNs\VMDKs are involved (and where exactly they come from) – Helvick Feb 13 '10 at 22:23
Unfortunately that is the description I got...! I only have rdp connection to the sql server which has wait problems...The actual description i got was also in german, otherwise i'd just print the whole thing...but that is the essence... – alex Feb 13 '10 at 22:34
up vote 0 down vote accepted

You're right, this appears to be a very poor storage and VM combination.

22 VM's running on a single 10 disk RAID 10 disk group is probably pushing things too far. A lot depends on what those VM's are doing though. That said if someone is concerned enough to think that they need to build their SQL Server partitions as you describe then they should be hosting all of its LUNS from separate RAID groups so that the objective of isolating the IO from the OS, Paging File and Database from each other is actually met. If all of the LUNS used for this are simply carved from the same RAID 10 Raid Group then there is nothing being gained. Whether this is necessary or not depends on how busy the SQL server needs to be, and how good the underlying SAN's disk array is.

If (as I suspect) that you mean someone is then taking multiple LUNs (or virtual disks) that are physically part of a single RAID group on the array and then combining them via Software RAID into logical volumes via software then that is a huge waste of effort and performance with absolutely no benefit. So to answer your question, no it's not normal.

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based on his description i too think that they are using software raid piggy backed from the hardware side which is indeed a waste. – user8256 Feb 14 '10 at 4:54

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