NetApp's WAFL with A-SIS (advanced single instance storage) does
this. From a quick google:
http://searchstorage.techtarget.com/originalContent/
0,289142,sid5_gci1255018,00.html says:
... calculates a 16-bit checksum for each block of data it stores.
For data deduplication, the hashes are pulled into a database and
"redundancy candidates" that look similar are identified. Those
blocks are then compared bit by bit, and if they are identical, the
new block is discarded.
The pre-sales engineer I spoke to regarding this said that it's not
done on demand but rather by a periodic background process. It's
pitched for backup and archiving functions. If you have NetApp kit it
can apply this to any of your data on the Filer, be it via CIFS, NFS,
FC or iSCSI.
While this isn't available on Linux it proves that there is market
demand for it, that it can be done and probably also appears to some
kernel hackers as a challenge...
cheers
Luke
On 06/12/2007, at 1:33 AM, rsivak@xxxxxxxxxxxxx wrote:
Is there such a filesystem available? It seems like it wouldn't be
too hard to implement... Basically do things on a block by block
basis. Store md5 of a block in the table, and when writing a new
block, check if the md5 already exists and then point the new block
to the old block. Since md5 is not guaranteed unique, might need
to do a diff between the 2 blocks and if the blocks are indeed
different, handle it somehow.
When modifying an existing block that has multiple pointers, copy
the block and modify the new block.
I know I'm oversimplifying things a lot, but something like this
could work, no? Would be a great filesystem to store backups on,
or things like vmware volumes...
Russ
Sent from my Verizon Wireless BlackBerry
_______________________________________________
CentOS mailing list
CentOS@xxxxxxxxxx
http://lists.centos.org/mailman/listinfo/centos
_______________________________________________
CentOS mailing list
CentOS@xxxxxxxxxx
http://lists.centos.org/mailman/listinfo/centos
