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dmdedup / dmdedup3.19

Device-mapper Deduplication Target
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How to use and run on UBUNTU #14

Closed v3nk1 closed 7 years ago

v3nk1 commented 8 years ago

Hi all, I am trying to do some IO operation on disk, which surely have no duplicated data whilst storing to disk. Here is the info I am able to compile module, inserted the module on OS running linux-4.4 kernel. Afterward did create dmsetup create mydedup and i am able to see /dev/mapper/mydedup and /dev/dm-0 device nodes. Then how to perform data operations? I tried mounting mydedup block device like this,

mount /dev/mapper/mydedup /mnt

It fails with error no filesystem, even tried /dev/dm-0 and /dev/sdbX also. Appreciate any points.

Thanks in advance, Venkatesh.

venkrishr commented 8 years ago

Did u format a new filesystem on mydedup? Like this:

mkfs -t ext4 dev/mapper/mydedup

The did u mention what filesystem u want? Like this :

mount -t ext4 /dev/mapper/mydedup /mnt

v3nk1 commented 8 years ago

Yeah, I did try that, but question here is, did it end up deduplicating filesystem installing(metadata like supernode, inode, structure) also? Since in driver we are just checking data, irrespective of anything. currently I am using dd for I/O operations.

venkrishr commented 8 years ago

No your question was

It fails with error no filesystem, even tried /dev/dm-0 and /dev/sdbX also.

Has that been resolved?

v3nk1 commented 8 years ago

Yeah, It was resolved. But my question still stands.. When i was using dm with filesystem installed, I see more dupwrites and writes than the data actually being copied. So It should not be like that, Right?? Suppose Lets assume i copy a file of 4096Bytes to mount point, it should increment write by 1(4K block). It is not happening as i showed but it increments more than 1. Why??

sectorsize512 commented 8 years ago

Hey, not sure you still need this answer, but dmdedup dedups all writes that go to it: file-system data, metadata, journal, etc.

sectorsize512 commented 7 years ago

v3nk1, any updates on this, or should we close the ticket? Thanks!

v3nk1 commented 7 years ago

Thanks for response. Is it a correct behavior that, dmdedup duplicates file system installation data also like inode and superbolck info also??

sectorsize512 commented 7 years ago

Yes, at this point it deduplicates everything. But in the future, we plan to avoid this. Here is corresponding paper:

https://www.usenix.org/conference/fast16/technical-sessions/presentation/mandal

Vasily

sectorsize512 commented 7 years ago

Closing the issue as it seems to be resolved. Reopen if needed.