SSY-V: recover DCS after desaster

Since DataCore's SSY-V is "only" a simple software running on Windows Server 2008R2 or 2012, you will probably run into a situation where your OS doesn't boot anymore or you lost your RAID or whatever problem could arise that renders one of your DCS inoperable.

What to do in such a situation? Well, you have three options, depending on what DR preparation you've made.

First introduced with SSY-V 8.0, DataCore offers a simple and easy to use backup tool that stores all configuration information in a predefined location. Normally you would configure the config backup on both hosts to store the files on a network share and run it automatically on aregular base. This is done with a SSY-V powershell CmdLet becasue in the GUI itself, there is no way to create a scheduler for this kind of task.

Regarding the network share you can use a central file server (e.g. your company filer or a NAS). Since the DCS normally won't be a member of a domain this can lead to some security "problems" becasue you have to store logon information inside the backup script. Second (and in my opinion the preferred) way is to map a share from the other DCS. Since the logon information on both DCS are normally the same you can automatically map und unmap shares within a script without storing any passwords in cleartext.

By using this kind of backup, bare-metal restores are quite easy to do as long as you use the same hardware. Restore is done by reinstalling the OS with all needed drivers, create some folders, copy the backup cab file to this folder and run the SSY-V installer. The installer will detect the config backup, import it and after a reboot the "new" DCS is back online. Of course, because of the crash you probably had there will happen a full recovery for all vdisks.

Nevertheless, this is quite simple and only needs a little time. Keep in mind that you should use a config backup that reflects the latest changes in your server group. So having a very recent backup is the key for a successful restore.

 

But what if you haven't a recent backup or none at all? Sometimes the script didn't work or you haven't setup a backup. Is there a way to recover? Yes, it is. Two ways to be correct.

The first way can be done manually by yourself. Do these steps at your own risk and only if you know exactly what you have to do. If this doesn't apply to you, please use the second method (see below) and contact DataCore support to help you.

If you still want to continue, here are the needed steps:

  • split and unserve any failed vdisk member
  • delete all unserved single vdisks from the crashed DCS
  • remove the crashed DCS fromt he server group
  • disable or disconnect all mirror ports from the still active DCS
  • disconnect all backend storage from the failed DCS
  • reinstall crashed DCS with same network information and name/workgroup
  • install the same SSY-V version as it was before the crash (should be the same as the still active DCS runs)
  • reconnect all backend storage to the new DCS
  • import storage pools on the new DCS
  • re-add the new DCS to the existing server group
  • reactivate licenses (you probably have to contact Datacore support for that becasue the same license is already registered at DataCore)
  • configure the server port roles
  • remirror all vdisks needed

Caveats for this method:

  • all vdisks have to be fully resynced (can take a huge amount of time depending on the amaount of data and resync speed)
  • if you had data protection in place for any vdisk, this information will be lost
  • all snapshots on the failed DCS are lost

Well, I think in such a desaster these caveats are easily acceptable to quickly get back a fully mirrored environment.

 

The second way to accomplish this is to contact DataCore support in such a situation. They will offer you a second way that doesn't need to split vdisks, therefore you won't have to remirror after the restore but nevertheless, after the failed DCS is back online, full recoveries will still take place. So the second way will not offer big advantages over the first method but will be the better way for all admis that don't know SSY-V that good to go the first way. Always contact DataCore support if you are in doubt or don't have an exact idea what step causes what reaction.

 

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