HAMMER de-dup in master

[Ilya Dryomov]

On Tue, Nov 09, 2010 at 12:26:03PM +0530, Siju George wrote:
> Ok I am running on
> 
> 2.9-DEVELOPMENT DragonFly v2.7.3.1468.gc4ce4-DEVELOPMENT #29: Mon Nov
> 8 16:39:43 IST 2010
> 
> and now I have
> 
> dfly-bkpsrv# hammer version /Backup1
> min=1 wip=6 max=5 current=4 description="New undo/flush, faster
> flush/sync (DragonFly 2.5+)"
> available versions:
>     1   NORM    First HAMMER release (DragonFly 2.0+)
>     2   NORM    New directory entry layout (DragonFly 2.3+)
>     3   NORM    New snapshot management (DragonFly 2.5+)
>     4   NORM    New undo/flush, faster flush/sync (DragonFly 2.5+)
>     5   NORM    Adjustments for dedup support (DragonFly 2.9+)
> 
> It is a backup server so Data is very important ;-)
> I have pfses running with mirror-stream between the first and second disks.

Again, since you are saying that your data is very important my advise
would be to not upgrade at all.  You can perfectly run v4 -> v4 streams
running latest master.  The upgrade does not bring in any performance
improvements or anything at all, except it allows one to run hammer
dedup command, which is currently considered *highly* experimental.

If you really want to upgrade your filesystems to v5 wait at least until
Matt MFCs v5 support into stable branch (it should happen in a week or
two).

> So as when I upgraded from 3 to 4 I guess these steps will be the
> right thing to do?
> 
> 1) Stop all Mirror Stream Processes
> 2) Upgrade the disk containing the slave pfses to hammer  ver 5
> 3) Upgrade the disk containing the master pfses to hammer ver 5
> 4) Re start mirror-stream processes

Dedup addition is basically a new ioctl and userspace sub-command, so
the upgrade procedure should be the same.  If this worked for you during
v3 -> v4 upgrade it should work now.

> After I upgrade the mother Filesystem should I induvidually upgrade
> the pfses too?

No, you don't need to upgrade each PFS individually.  hammer
version-upgrade command operates on the entire HAMMER filesystem.

Thanks,

		Ilya