Storage Spaces File Recovery

In most cases, Storage Spaces uses the thin provisioning feature. Thin provisioning significantly complicates data recovery since it leads to fragmentation of the spaces. So apart from typical problems with location and fragmentation of files at the filesystem level, it is also needed to take into account fragmentation of spaces on the physical drives in the pool. Therefore, recovering files from a space may often require recovery of Storage Spaces configuration first. However, there are cases when Storage Spaces recovery is not required:

• you deal with filesystem failure when underlying virtual disks (called spaces) work as they should (Storage Spaces RAW file system issue);
• you accidentally deleted a small amount of data (for example, just a couple of small files) from the space and now want to undelete the files.

As shown in the diagram below, if you delete large number of small files on a space, say, File 2, File 4, File 5, and File 6, data recovery software can recover only File 2. Files 4, 5, and 6 are not recoverable by the means of regular data recovery. Once you delete these files, the Storage Spaces driver considers slabs with file contents as free and therefore available to be used in other spaces. In this scenario, regular data recovery software has no chance to extarct these deleted files.

In all these cases Storage Spaces works normally and lists the spaces as "green" (or "yellow") and with the allocated sizes you expect for these spaces. To undelete a file or fix RAW file system issue it is enough to use regular data recovery software which will operate with the space in the same way as with a regular hard disk. Note that if Storage Spaces shows that allocated size for a space is less than it should be, it means that the Storage Spaces driver has already withdrawn slabs from the space and therefore file recovery is not going to work. If this is the case, you need a full-scale Storage Spaces recovery first.

Once you are sure it makes sense to try typical file recovery, just download and install any regular data recovery tool like ReclaiMe File Recovery, then select the needed space in the Logical drives section and see what it brings. However, you may face the following problems:

• The size of storage pool may easily reach dozens of terabytes. Since all data recovery tools only copy data to a new storage device, you will need free space of the same size as the original pool. Additionally, the more capacity of the pool, the more time copying will take.
• If the pool comes from Windows Server 2012, it may use ReFS filesystem. As of February 2013, ReFS data recovery is not very well understood and there are few tools available on the market for it (although we do have one).

Storage Spaces specifics in Windows 8

Storage Spaces in Windows 8 unlike Storage Spaces in Windows Server 2012 doesn't implement an easy GUI method to create a fixed space. Instead, all the spaces are thinly provisioned by default.

From the recovery point of view it means that once you format the space or just delete big enough chunk of data from it you can no longer get the data using regular file recovery software. You need a full scale Storage Spaces recovery which tries to match slabs on the pool member physical drives to the spaces.

From a user point of view, deleting data from a thinly provisioned space is like deleting data from an SSD which uses TRIM command to actually zero-fill data blocks. Once you delete data on a thinly provisioned space or just format such a space, the Storage Spaces driver immediately "forgets" about all the slabs containing the deleted data. If after deleting you look at the allocated size the driver reports for the space, you see that it is either some very small value for the formatted space or less than it should be for the size of the deleted data in case of data deletion.