2-way Mirror?

jwaterman · Thu Oct 11, 2007 10:12 pm

I know files written to a target which is mirrored get written to the mirrored target, but do files written to a mirrored target get written to the original target?

For example, if I set up a target (NAS1) which is mirrored to another target (NAS2) on another host, and NAS1 goes down, but I still write to the target on NAS2 while NAS1 is being brought back online, will they sync up when NAS1 comes back, or is the mirroring only one-way? Is it even possible to write to the mirrored target (NAS2) directly?

Thanks,
Joel

Fri Oct 12, 2007 11:34 am

Hi.

If active mirror fails and later backs online it is marked as invalid. In this situation you should switch the active mirror to the valid (second) one (press the right mouse button over the mirror device and select "Switch Active Mirror..." option) and perform synchronization manually (press the right mouse button over the mirror device and select "Check and synchronize..." option).

jwaterman · Fri Oct 12, 2007 2:03 pm

Ok, that is good to know. Are there any plans to automate this type of failback behavior?

Sun Oct 14, 2007 10:23 am

How do you want to automate it? Can you provide step-by-step actions performed by both sides?

jwaterman wrote:Ok, that is good to know. Are there any plans to automate this type of failback behavior?

jwaterman · Mon Oct 15, 2007 8:32 pm

I am looking for a behavior where one mirror is a mirrored backup of the other (in real time). Such that, if I have 2 targets, NAS1 and NAS2, I want to write to NAS1 when its available, and have NAS2 be as close to a live backup as possible, so if NAS1 becomes unavailable, NAS2 can take all of the new "live" writes. When NAS1 becomes available again all "live" writes will go there again, but I need all the data written to NAS2 in the meantime to be sync'ed back to NAS1 so they are identical again.

I guess I first need to know if mirroring is real-time, or do I have to perform the "check and synchronize" operation to get them replicated? If it is in real-time (or close to it), why can't the synchronizing back up be automatic?

Tue Oct 16, 2007 1:20 pm

If you have NAS configured you need software for file replication.
And about the SAN: when the first mirror of mirror device becomes available again we need to be sure that the physical device is ok.
If it has some problems it can cause mirror device fail after several automatic synchronizations. So we think that administrator should perform the procedure of switching active mirror and synchronizing mirrorâ€™s data manually.