SNAPCNT2 vs SNAPCNT3: is there a way to migrate? Is there any advantage?

[Chiem Ma]

I was looking at my content.lst with a hex editor and found the first few bytes contain 'SNAPCNT2'.

The source says of SNAPCNT3:

:          *  - SNAPCNT3/SnapRAID 11.0 Adds entry 'y' for hash size.
:          *  - SNAPCNT3/SnapRAID 11.0 Adds entry 'Q' for multi parity file.

Is there any advantage to SNAPCNT3? If so, is there a way to migrate to it other than doing a complete rebuild of parity? If I do need to rebuild parity, is there a way to keep the old hashes around so I don't have to rehash everything?

The only safe method I could think of was:

• Add a new drive for the new parity
• Rename content.lst --> content.lst.old
• Modify snapraid.conf to point parity at the new drive
• Do a sync to rebuild everything
• Rename content.lst --> content.lst.new
• Rename content.lst.old --> content.lst
• Modify snapraid.conf to point parity at the old drive
• Do a check to be sure nothing changed
• Rename content.lst --> content.lst.old
• Rename content.lst.new --> content.lst
• Modify snapraid.conf to point parity at the new drive
• Dispose of the old parity and content.lst.old file safely, move or remount the parity drive if you wish, modify conf as necessary.

which involves two full passes on the data (48 hours total for me). It would be awesome if there's a way to directly convert content.lst, but I'd also settle for just to knowing that converting the file won't gain me anything and I should ignore this.

Thanks,

Chiem

[Andrea Mazzoleni]

Hi Chiem,

The version 3 is used only with split parity. If not, the version 2 is preferred because it's compatible with older snapraid versions.

Anyway, if snapraid needs to use version 3, the migration will happen automatically and transparently.

Ciao,
Andrea

[Chiem Ma]

Ah! Thanks so much.