Re: Send/Receive Use Case

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On Fri, Jul 10, 2015 at 03:03:27PM -0400, Vincent Olivier wrote:
> actually I have another question : is it posssible for a RAID0 fs to “receive” from a “sending” RAID10 ? 

   Yes, definitely. I do my backups from RAID-1 to single. The send
stream format is based on files, not on the underlying raw storage.

   Hugo.

>or do they need to be of the same replication scheme too ?
> 
> 
> 
> > On Jun 27, 2015, at 10:34 AM, Vincent Olivier <vincent@xxxxxxx> wrote:
> > 
> > ok i’ll go home and rethink my life then ;)
> > 
> >> On Jun 27, 2015, at 10:21 AM, Hugo Mills <hugo@xxxxxxxxxxxxx> wrote:
> >> 
> >> On Sat, Jun 27, 2015 at 10:04:28AM -0400, Vincent Olivier wrote:
> >>> Hi,
> >>> 
> >>> There are 4 things I’m not sure about re:send/receive.
> >>> 
> >>> 1) Is it possible to first copy things on a file system using rsync and then use send-receive ? And to subsequently mix rsync and send-receive ? Provided that snapshots are made accordingly.
> >> 
> >>  Probably. It depends on exctly how you want to use them.
> >> 
> >>> 2) Is possible to “send" a snapshot diff to disk and then “receive" it from the said disk into a remote filesystem ? I have two very large and physically distant btrfs filesystems. It would be more economical to juste dump snapshot diffs to disk for transport instead of the network.
> >> 
> >>  Yes, that's perfectly possible.
> >> 
> >>> 3) How are “conflicts” handled by send-receive if at all ?
> >> 
> >>  There are no conflicts possible, due to the requirement of all the
> >> subvolumes involved in the send/receive process being read-only.
> >> (Actually, that's not quite true -- you can make a subvolume
> >> read/write, and then read-only again. In that case, the receive will
> >> probably fail, leaving the received subvolume in a partially-created
> >> state).
> >> 
> >>> 4) If a file is created, modified and then deleted in-between two
> >>> snapshots is it ignored by send/receive or does send/receive
> >>> "re-enacts” the journal exactly ?
> >> 
> >>  It'll be ignored. The FS doesn't keep track of how it reached a
> >> particular state -- only what that state is.
> >> 
> >>  Hugo.
> >> 

-- 
Hugo Mills             | UNIX: Japanese brand of food containers
hugo@... carfax.org.uk |
http://carfax.org.uk/  |
PGP: E2AB1DE4          |

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