diff options
Diffstat (limited to 'docs/block-replication.txt')
| -rw-r--r-- | docs/block-replication.txt | 28 |
1 files changed, 18 insertions, 10 deletions
diff --git a/docs/block-replication.txt b/docs/block-replication.txt index 6bde6737fb..108e9166a8 100644 --- a/docs/block-replication.txt +++ b/docs/block-replication.txt @@ -65,12 +65,12 @@ blocks that are already in QEMU. ^ || .---------- | || | Secondary 1 Quorum || '---------- - / \ || - / \ || - Primary 2 filter - disk ^ virtio-blk - | ^ - 3 NBD -------> 3 NBD | + / \ || virtio-blk + / \ || ^ + Primary 2 filter | + disk ^ 7 Quorum + | / + 3 NBD -------> 3 NBD / client || server 2 filter || ^ ^ --------. || | | @@ -106,6 +106,10 @@ any state that would otherwise be lost by the speculative write-through of the NBD server into the secondary disk. So before block replication, the primary disk and secondary disk should contain the same data. +7) The secondary also has a quorum node, so after secondary failover it +can become the new primary and continue replication. + + == Failure Handling == There are 7 internal errors when block replication is running: 1. I/O error on primary disk @@ -171,16 +175,18 @@ Primary: leading whitespace. 5. The qmp command line must be run after running qmp command line in secondary qemu. - 6. After failover we need remove children.1 (replication driver). + 6. After primary failover we need remove children.1 (replication driver). Secondary: -drive if=none,driver=raw,file.filename=1.raw,id=colo1 \ - -drive if=xxx,id=topxxx,driver=replication,mode=secondary,top-id=topxxx\ + -drive if=none,id=childs1,driver=replication,mode=secondary,top-id=childs1 file.file.filename=active_disk.qcow2,\ file.driver=qcow2,\ file.backing.file.filename=hidden_disk.qcow2,\ file.backing.driver=qcow2,\ file.backing.backing=colo1 + -drive if=xxx,driver=quorum,read-pattern=fifo,id=top-disk1,\ + vote-threshold=1,children.0=childs1 Then run qmp command in secondary qemu: { 'execute': 'nbd-server-start', @@ -234,6 +240,8 @@ Secondary: The primary host is down, so we should do the following thing: { 'execute': 'nbd-server-stop' } +Promote Secondary to Primary: + see COLO-FT.txt + TODO: -1. Continuous block replication -2. Shared disk +1. Shared disk |