It took me some time to fully understand how snapraid works. Even though it’s quite simple. Similar to unraid, parity is calculated and stored on one (or more) parity disks. Each data disk uses a normal filesystem and you can just pull it out of the Server and mount it somewhere else. So far so good. But instead of using the whole disk, snapraid works on a file basis. Meaning it works on files and folders and not necessarily the whole disk. In the snapraid.conf you have to specify the watched folders or mount points.
The question was then: does snapraid work with Drivepool (or similar pooling application) and how do I configure it? Well of course it does work with Drivepool, but you don’t point it to the Drivepool but to the physical disks directly. You also don’t need to point it to the hidden drivepool folder, just the root of disk is fine too (if you want to use the whole disk). Just be sure to use the default values for #nohidden (you don’t want that enabled!) and it’s probably a good idea to use the default exclude list.
Example with one OS drive (C:), three data drives (D:,E:,F:) and one Parity drive (G:)
parity G:\snapraid.parity content C:\snapraid\snapraid.content content D:\snapraid.content content E:\snapraid.content content F:\snapraid.content disk d1 D:\ disk d2 E:\ disk d3 F:\ # Excludes hidden files and directories (uncomment to enable). #nohidden
For the rest keep the defaults.
Now on to the configuration of Drivepool. Put all your Serverfolders on the Pooldrive. You can change the Pooldrive drive letter using Computer Management, just as you would with a normal harddrive. In Drivepool you want to switch off drive balancing, because you don’t want data to be moved from one drive to another.
Rather configure file placement based on folders. For example allow your movies to go on any of the three drives, but limit other folders to one drive. It will still move to another drive if the current one is too full (you can configure this in the file placement as well).
For snapraid there’s a great helper script out there for Windows Powershell: https://snapraidhelper.codeplex.com/
Be aware there is another old version around as well, but this one if the extended one from therealjmc. It’s also well documented.
To run snapraid helper script using the task scheduler you might want to check out this page: http://community.spiceworks.com/how_to/show/17736-run-powershell-scripts-from-task-scheduler
I configured my two tasks. One that runs the helper script daily (except on Sundays) without parameters and another task that runs only once a week (on a sunday, duh) with the syncandscrub command. The 2nd task also wakes up the server and since I use lights-out it will monitor snapraid.exe and puts the server back to sleep again once it’s finished.