zfs discuss - Mar 2012 - zrep initial release (replication with failover)

I''m happy to announce the first release of zrep (v0.1)

http://www.bolthole.com/solaris/zrep/

This is a self-contained "single executable" tool, to implement
synchronization *and* failover of an active/passive zfs filesystem
pair.
No configuration files needed: configuration is stored in the zfs
filesystem properties.

Setting up replication, is a simple 2 step process
(presuming you already have root ssh trust set up)


  1. zrep init pool/myfs remotehost remotepool/remotefs
      (This will create, and sync, the remote filesystem)

  2. zrep sync pool/myfs
      (or if you prefer, zrep sync all)
   Do this manually, or crontab it,or....

will automatically switch roles, making the src, the destination, and
vice versa.

You can then in theory set up "zrep sync -q SOME_SEC all"
as a cronjob on both sides, and then forget about it.
(although you should note that it currently is only single-threaded)

Failover is equally simple:

  zrep failover pool/myfs


zrep uses an internal locking mechanism to avoid problems with
overlapping operations on a filesystem.

zrep automatically handles serialization of snapshots. It uses a 6
digit hex serial number, of the form
  @zrep_######
It can thus handle running once a minute, every minute, for 11650
days. Or, over 30 years

By default it only keeps the last 5 snapshots, but that''s tunable via
a property.



Simple usage summary:
zrep (init|-i) ZFS/fs remotehost remoteZFSpool/fs
zrep (sync|-S) ZFS/fs
zrep (sync|-S) all
zrep (status|-s) [ZFS/fs]
zrep (list|-l) [-v] [ZFS/fs]
zrep (expire|-e) [-L] (ZFS/fs ...)|(all)|()
zrep (changeconfig|-C) ZFS/fs remotehost remoteZFSpool/fs
zrep failover [-L] ZFS/fs
zrep takeover [-L] ZFS/fs
zrep clear ZFS/fs  -- REMOVE ZREP CONFIG AND SNAPS FROM FILESYSTEM