When setting up a new VM is there any merit to adding multiple virtual hard drives (e.g. one for OS files, and another for application/data files) rather than creating one large virtual hard drive? I've always setup physical servers with one set of disks for the OS files and another set of disks with the data files for IO paging and redundancy reasons. With virtual hard drives do these advantages still apply?
Here's some reasons I used separate disks instead of partitions or one big Disks
Reason Not to:
If for some reason your vmx file becomes corrupted or is missing. It may make finding all the disks that make up your VMs difficult and understanding what order they need to go back together. (if you have a back up the vmx file and the VMs this isn't a problem)
Typically I Create VMs with an OS partition and a Data partition (aligned) on the same datastore. If there's reason to move them I do. Mostly it's the simplicity of expanding storage in the VM. If multiple Disks are required ( SQL, Temp/logs/backup/Data) I just create individual disks for each. Even though you have multiple disks you can manage them all from the VM level.
There's very little downside to multiple disks
Hope that helps
-Rich
Hello.
Best practice is the same in the virtual machine as it is in the physical - Separate volumes for OS and data. Having different VMDKs also allows you greater flexibility later on. I don't usually separate the pagefile volume out, but there could be valid reasons to do that as well.
Good Luck!
I only separate OS and data if it is for a server that requires a lot of data like a database. If the os and data needs do not exceed 50GB or so I make it one disk. I've havent had any issues so far. I honestly dont see the point in separating unless a new drive was requested after the initial VM was creates, or you plan to have the data on slower cheaper disks.
Also on physical system you want to use different volumes for different type of data.
In a virtual environment there can more reason to make more volumes (and each volume = 1 vmdk):
Andre
Here's some reasons I used separate disks instead of partitions or one big Disks
Reason Not to:
If for some reason your vmx file becomes corrupted or is missing. It may make finding all the disks that make up your VMs difficult and understanding what order they need to go back together. (if you have a back up the vmx file and the VMs this isn't a problem)
Typically I Create VMs with an OS partition and a Data partition (aligned) on the same datastore. If there's reason to move them I do. Mostly it's the simplicity of expanding storage in the VM. If multiple Disks are required ( SQL, Temp/logs/backup/Data) I just create individual disks for each. Even though you have multiple disks you can manage them all from the VM level.
There's very little downside to multiple disks
Hope that helps
-Rich
Another downside to a single volume (or VMDK) approach is the issue of some errant app or logging filling up your OS volume.
If you are going to create seperate volumes , its worth considering putting them on seperate vSCSI controllers - you can then use the paravirtualised one ( for the non System partition ) and get a little bit of "free" performance.