Data Recovery Weekly

Some do actually like non-standard hardware and software setups. If we build a 16 TB RAID 5 (9x 2TB), can we then install Windows on it? Probably yes, with some U/EFI trickery, but then troubleshooting this contraption if hardware ever dies would be a nightmare with 9 drives. Now another try We have a leftover of drives, like all sorts of 160GB to 2TB Parallel ATA, all sorts of Serial ATA, five RAID/HBA controllers, and a motherboard. We thought of putting it all together and deploying ZFS over it. Do you think it is a good idea? Actually, no. The complexity of the failure modes for the proposed design is just mind-boggling. First of all, when ZFS crashes, there is no reliable data recovery for it. Then, multiple HBA/RAID cards from different vendors in the same system are not going to work stable. More then, with a different size drives, no common RAID scheme can be applied. Should the RAID fail, the system is not recoverable. OK you can go with ZFS hybrid filesystem-RAID capability, ...

Some new technologies have side effects which decrease data redundancy. Such technologies are: NTFS compression Windows Vista/7 vs. Windows NT/2000/XP complete format TRIM on SSDs ZFS deduplication Initially, the effect of decreasing redundancy is unnoticeable, but once the technology becomes popular, the unintended consequences appear. Volume-level NTFS compression never became widespread among home users. As Windows Vista and then Windows 7 become widespread, the number of cases when data is lost irreversibly due to reinstallation increased. You can recover some data after XP reinstallation, but not after Vista/7 reinstallation with a complete format. SSDs with TRIM are not widespread enough (yet) to notice that data recovery software does not properly work with them. As for ZFS-based NASes, then on the one hand they are not widespread among the home users, on the other hand - even the first installations did not yet reach the end of their service life.

Data recovery software is based on the filesystem and user data redundancy. In case of significant filesystem damage user data redundancy is often required for data recovery software . Elimination of user data redundancy using a compression (as in NTFS) or a deduplication (as in ZFS) complicates automatic data recovery.