Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
Mark Watts schrieb:
>> I just want to replicate a SAN (array, disk etc.) to another physical
>> location.
>> There is no sense in using heartbeat for me, as when that primary SAN
>> dies, the asymmetric link from another datacenter will be too slow
>> anyway to provide services.
>
> Why not use rsync or some other replication that runs on a periodic basis?
> It actually sounds like DRBD is overkill here.
rsync does not work for block devices.
All other similar tools will certainly give unpredictable results if it
copies a file (or block device) to which someone still appends data.
Another alternatives I considered:
1. RAID-1 over iSCSI - can be problematic when network connection is
dropped or there are disconnections
2. distributed storage / dst - doesn't seem ready yet
So it seems to me that drdb is the best choice?
>> So, if I want to replicate a local array to another machine, should I
>> use 127.0.0.1 address in drbd.conf?
>
> No - use the real network address of the node. (Connections to that IP from
> the local box will be dealt with internally by Linux anyway - data will never
> hit the network hardware).
>
>> resource drbd0 {
>> protocol C;
>> incon-degr-cmd "halt -f";
>>
>> on thost1 {
>> device /dev/nb1;
>> disk /dev/hda7;
>> address 127.0.0.1:7789;
>> }
>>
>> on thost2 {
>> device /dev/nb1;
>> disk /dev/hda7;
>> address 10.1.1.32:7789;
>> }
>> }
>>
>
>
>> And what happens if your heartbeat box dies? ;)
>
> Heartbeat runs on both nodes and they send monitoring packets (heartbeats) to
> each other on a very frequent basis. Should one node die, the other will take
> over. [ "die" is defined when the Secondary node can no-longer communicate to
> the Primary node in any way. If you only have one network link between the
> nodes, and that dies your cluster will go split-brain unless you have some
> form of out-of-band fencing system in place. ]
Hmm, maybe indeed I'll consider heartbeat. Sounds like there are only
wins here, with a minor one-time configuration effort.
--
Tomasz Chmielewski
http://wpkg.org