Greyhole + SnapRAID

[modem7]

Hey guys,

Does/has anyone used Greyhole + SnapRAID (or similar)?

Greyhole seems to be quite inefficient use of redundancy storage, and I was thinking using both Greyhole and something like SnapRAID would be better.

Greyhole to distribute files across the pool, and SnapRAID to create redundancy.

Would be good to get some feedback!

[bigfoot65]

Never heard of SnapRAID. Do you have a link?

Not sure I understand what you mean by "Greyhole seems to be quite inefficient use of redundancy storage." It provides per share redundancy over multiple drives. Isn't that what RAID does as well without all the headaches.

http://www.greyhole.net/

[modem7]

http://snapraid.sourceforge.net/

The way I see it (please feel free to correct me!), is that Greyhole (much like Raid 1), would use 50% of my disk space (assuming 1 redundant copy (so 2 copies total of one file)).

So, if I had 5 disks with 2TB each (for discussion's sake), I'd have 10TB total disk space;

With Greyhole, I'd get to use 5TB with 1 copy redundancy (simplifying it to correlate to RAID 1).

With RAID 5 (Parity), I'd get to use around 8TB of disk space (including parity that you'd get with SnapRAID (or similar)).



So the idea would be: Use Greyhole for the drive pooling + LZ, and use SnapRAID for the parity redundancy.

Am I on track, or completely deluded?

[bigfoot65]

That sounds about right. Greyhole takes up space on 1 disk for the master file and on each additional one for a copy if specified. Greyhole only uses space for files, so unless you have 2.5TB of data with max copies, you would still have 7.5TB of free space. Also need to remember space used in the LZ is freed up from those files as Greyhole moves them, so additional space would be available.

The SnapRAID sounds interesting. One thing I did notice is it mentions use for a system with files that rarely change. Not sure how it will be have in conjunction with Greyhole, but probably worth a test.

My preference would be to stick with Greyhole as it keeps things simple and disk storage is cheap compared to years ago. Adding additional software may just make things more complicated just to save some storage space. Performance may be impacted as well.