In a previous blog post I mentioned that Volume Shadow copies cannot be trusted if they are stored on the same disk that you’re trying to protect. If you do, the very act of attempting to restore a previous version of a file can overwrite the storage location where the volume shadow copy is kept – especially when disk space is low.
After a few hours on the phone with a Microsoft Tech, they basically said that’s how it’s supposed to work! The only way to avoid the issue: Install a different set of physical disks and dedicate that space to the shadow copies.
So, here’s how I accomplished that:
In my case I had 5 TB of data in a RAID 6 storage array that I wanted to protect with shadow copies. A lot of time had elapsed since I purchased the array and I still had some storage bays available. now with storage being very inexpensive, I was able to purchase QTY = 2, 2TB Hard Disks for just a few hundred dollars.
I installed the disks into my array as a RAID 0 stripe – they’re just for shadow copies so I’m not overly concerned with redundancy on these puppies…. Likewise since this will never be used for production data, I also purchased the slowest / cheapest possible disks – mine were 5400RPM disks.
To stop users from using the disks, I brought the disk online and formatted it as an NTFS disk, but I purposely did NOT assign it a drive letter nor a mount point:
I called the volume “ShadowCopies” to make it easy to identify.
Chose the Properties option, then Shadow Copies, selected the volume and then clicked Settings…
On the settings dialog, under “Storage area” I picked the un-mounted Volume from the “Located on this volume” pick list of drives.
Scheduling the Creation of Shadow Copies
Once the volume was selected, I clicked the schedule button, then clicked “New” to create a new schedule, selected Weekly, picked days: Monday to Friday (our office doesn’t usually have people working the weekends), and then specified a time of day:
I repeated that process for each time of day when I wanted a snapshot to occur.
So now, users can revert to previous versions of files from 7AM, 12PM, 4PM, and 9PM in my example.
And since the shadow copies are stored on a physically separate disk, I no longer have to worry about them being overwritten by the very process of restoring from the shadow copy!
Backing up .VHD files
Backup Exec also often has a problem backing up .VHD files (Hyper-V Virtual Hard disks) if you don’t have enough space on the volume where the disk is located to create the volume shadow copy. By using a separate set of physical disks I should also be able to avoid that issue.
Allowing End-Users to restore their own files
For those of you not already aware, the real beauty of Volume Shadow Copies is the idea that you can empower your staff to restore their own files without involving you, the IT person.
To restore a previous version of a file, the end-user simply has to bring up the properties of the file, and click the Previous Versions tab:
In this example, the previous version of the file was from way back in 2004. The shadow copy only consumes additional space when the file has changed between the time when the original shadow copy was taken and now. So for documents that don’t change very often, you end up with a minimal number of previous versions.
Give it a try and let me know if it saves you any time or streamlines your backups!