On 25/04/14 05:06 AM, Velko wrote:
Hello,
I'm planing to use DRBD for DR and since I've never used it, I have a
few questions.
1. Have anyone used it for replication to different data center (both
east coast of USA)? I was thinking of using protocol A without DRBD
proxy (maybe protocol B). How does it work in real life?
You would want Protocol A, or else your storage performance would
effectively drop to the same speed as the network. Of course, the
trade-off is that the remote side will often be a little behind
production (or a lot behind, depending of how much data is being written
compared to the network speed).
2. Since there is a lot of 2-3 MB files in size of 1GB daily that are
not that important in case I need to switch to secondary site, would it
be possible to put those files on separate partition (DRBD device) and
configure it to have lower priority? Maybe only periodicaly
resynchronization? I understood that it is much more efficient.
Partition with less changing files and InnoDB tables would have high
priority.
Not easily. I suppose you could create a separate resource which would
use a different port and then try QoS, but that could get tricky (in
general, not DRBD specific, QoS can be a pita).
3. Would having separate NIC for replications improve performances in
this case?
Depends entirely on where your bottle-neck is. I suspect that will be
your WAN connection, which you didn't talk about. ;)
4. Is it possible to configure DRBD to automatically demote in case of
loosing internet connection?
Not safely, no. There is now reliable way to use fencing, and without
reliable fencing, only a human can ensure the state of the lost node. To
try and automate it would very likely lead to split-brains.
--
Digimer
Papers and Projects: https://alteeve.ca/w/
What if the cure for cancer is trapped in the mind of a person without
access to education?
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