I have a server that is connected to a SAN (Dell Compellent) and due to space concerns I am looking into installing some physical disks into this server to 'offload' some data being used by the server on the SAN. The server has several volumes using the SAN, one of which is the OS/system drive. I want to leave this on the SAN, but replace all other volumes with the physical disks.

I plan to clear the disks beforehand using another server, and also to install them offline (i.e. not hotplug them) for safety.

My question is - Will simply plugging the disks in be ok (And will I then be able to format and configure them in disk manager in windows) or do I need to configure them using the RAID configuration software that loads before the OS (I have very little experience with server RAID setup)

The server in question is a dell poweredge 1850 (not sure which generation at the moment) running windows server 2008 Standard.


I believe it will depend entirely on the RAID controller. I know that there's no way to configure my HP P212 controller in 'pass-through' mode, so a new disk that's plugged into the controller has to be configured as a single-disk volume, before the OS sees it as a disk.

That said, there are controllers that do enable unconfigured disks to be exposed directly to the OS without any RAID configuration needed.

It's interesting that you want to move data off the SAN, but leave the system disk on the SAN - I'd guess that most people would want to do this the other way round. SANs tend (!) to be well managed, resiliant, backed up etc. A system drive is easily-rebuildable, whereas people's data isn't.

I'd also argue that in a production hosting environment, you'd want all locally attached disks to be in RAID 1 (mirrored) for the sake of resilience, unless you've got a very good reason for doing so.

  • It's a unique situation - I want a short term way of freeing some 'pressure' from the san, but a rebuild of the OS would be time consuming (requires a team effort because we have a company that runs the website that the server hosts). The other volumes in question are a log drive, a pagefile drive, and something else, but none of them have critical data on them. In time the whole server will be virtualized and using a different SAN. – MrVimes Jan 25 '13 at 10:24
  • Absolutely, if it's what your requirements need, go for it. As long as your critical data is as safe as you think it is :) – growse Jan 25 '13 at 10:27

Just plugging them in should be enough, of course we'd always recommend you RAID them for safety (and perhaps performance) first if you can but your plans should be just fine.

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