FileGriffon and SnapRAID: Array Parity vs File-Level Verification

If you have spent much time in home-server or data-hoarding communities, SnapRAID comes up frequently, and with good reason. It is free, open source under GPLv3, actively developed, and has protected large media arrays for years.

It also shares a capability with FileGriffon: hashing your data and using those hashes to detect silent corruption the filesystem never reports. The overlap is genuine, so it is worth comparing the two honestly instead of pretending the products occupy completely separate worlds.

In short: SnapRAID protects an array you design. FileGriffon monitors storage you already have. The better fit depends much more on your setup than on any list of features.

What SnapRAID actually does

SnapRAID calculates parity across several independent data disks and keeps it on one or more dedicated parity disks. Given enough parity, it can rebuild a failed data disk, with support for up to six simultaneous disk failures depending on the array configuration.

Several details from SnapRAID’s own manual matter to this comparison:

• It is snapshot parity, not real-time RAID. snapraid sync reads every modified file and updates parity to match. Recent changes are not covered until that sync finishes. Files added after the last sync are not protected, although their presence does not stop recovery of files that were already synced.
• snapraid scrub is the integrity check. Each run checks roughly 8% of the array against checksums calculated earlier, while skipping anything scrubbed within the past 10 days. Bad blocks are marked and can be repaired using snapraid fix.
• snapraid fix restores the last synced state. It compares files and parity with the snapshot from the previous sync and reverts any differences.
• Parity disks have a minimum size. The parity space must be at least as large as the biggest data disk in the array.
• It is aimed at files that change infrequently. SnapRAID’s own documentation describes it as primarily intended for home media centers and large arrays containing files such as movies, music, and photo archives.

That is not criticism. These are intentional design choices that make SnapRAID highly effective at the job it was created to do.

What FileGriffon actually does

FileGriffon operates as a Windows background service and monitors what it calls vaults. A vault may be an entire drive, one folder, a NAS share, or even a single file. You do not need to design an array or set aside a parity disk.

Using XXH3-64, the initial scan saves a hash for each file it tracks. Subsequent scans recheck the files according to the schedule set for that vault, then record the result: VERIFIED when a file continues to match its baseline, CORRUPT when its contents have changed unexpectedly, and MISSING or MOVED when files disappear or are reorganized. When a change is intentional, you Accept it to make that the new baseline.

If you need recovery rather than detection alone, you can enable parity protection per vault. It generates PAR2 recovery data with Light (5%), Standard (10%), or Archival (20%) redundancy. This is per-file parity stored alongside the files, rather than array-wide parity held on a dedicated disk.

Side by side

	SnapRAID	FileGriffon
Shape	Parity across a multi-disk array	Per-file verification of chosen folders, drives, or shares
Setup required	Design the array, allocate parity disks, write a config	Point it at a folder or drive
Corruption detection	Checksums, verified during sync and scrub	Scheduled per-file hash comparison
Recovery from a dead disk	Yes, within the array’s parity limits	No
Recovery from partial file damage	Yes, from parity	Yes, from PAR2, within the redundancy level chosen
Works on a single drive	Not the intended use	Yes
Works on a NAS share	Not the intended shape	Yes
Frequently changing files	Explicitly not the target workload	Handled, with Accept for intentional edits
Scheduling	Via the daemon, cron, or your own scripts	Built in, per vault
Platform	Cross-platform	Windows, macOS in development
Price	Free, GPLv3	Free tier, paid tiers for more

When SnapRAID is the better choice

Put simply, if you run a multi-disk media array and need protection from an entire disk failing, SnapRAID is likely the right choice. FileGriffon does not replace it.

FileGriffon cannot solve “one of my eight drives failed, rebuild it.” That is precisely the problem array parity is designed to address, and SnapRAID handles it well, for free, backed by years of operational history. If SnapRAID already protects your pooled media library, you are comfortable with sync and scrub, and the content rarely changes, then you already have coverage for the failure modes it handles. An additional tool does not make a sound storage design twice as correct.

SnapRAID also costs nothing and works across platforms, and both advantages matter.

When FileGriffon fits better

The gap left by SnapRAID is not a weakness in SnapRAID. Array parity simply presumes an array.

Plenty of storage does not have that shape. Consider a single external archive drive, a folder of completed client work on a workstation, a NAS share available over SMB that you do not administer, or a collection of disconnected disks plugged in only a few times each year. In those cases, there is no array across which to build parity, and creating one would be a far bigger commitment than the problem justifies.

FileGriffon also monitors at a level array parity does not. Its per-file history can show that a particular file changed, when it was last verified, whether it moved instead of vanishing, and whether you made the change intentionally. That file-level lifecycle provides different information from “a block failed its checksum.”

It also handles scheduling and reporting without requiring you to build the automation. That is less important to someone who already maintains cron jobs, but more useful to someone who wants their photo archive checked without becoming a storage administrator.

Using both is reasonable

The tools are not mutually exclusive, and dividing the work between them can make sense.

SnapRAID can protect the pooled array from disk failure. FileGriffon can monitor what remains outside it: external archive drives, working folders on your desktop, a NAS share from another machine, and disks connected only occasionally. They are different layers addressing different failure modes.

One warning bears repeating: neither tool is a backup. SnapRAID parity offers no help if the array and its parity are lost together, while FileGriffon’s PAR2 data cannot help when the drive containing both the file and its parity fails. Both provide integrity and partial recovery on top of genuine backups, rather than replacing them. Our guide to the 3-2-1 backup rule explains what that foundation looks like.

The honest summary

Both SnapRAID and FileGriffon rely on hashing to detect corruption that might otherwise remain unnoticed until the file is needed. They differ in what each one assumes about your storage.

SnapRAID expects you to build and maintain a parity array, offering whole-disk recovery in return. FileGriffon assumes you will not, providing scheduled verification and per-file parity on the storage you already use instead.

To understand the underlying failure behind all of this, see our articles on what bit rot actually is and file integrity monitoring as a broader practice. Both are relevant whichever tool you ultimately choose.