lvreducing mirrored database raw devices

[Diego Montanez]

Hello,

is it safe to lvreduce a mirrored database raw logical devices with said database in use? Or should we schedule a maintenance window for this. We want to migrate data from one XP array to another. Thanks in advance for any suggestions...

[Bill Hassell]

Whether the data on the lvols is raw or a bunch of files, the split will create an image exactly at that moment. If the database is busy, there will be broken chains, incomplete records, missing index entries, in other words, a mess. This is exactly what happens if the system crashes -- the data must be repaired. Database recovery may take hours to days depending on how damaged it is.

You must stop all activity in the database (place it in read-only or backup mode). Then split the lvols and once completed (a few seconds if you script the tasks), you can start the database again. If you are unsure of how to change the databse state, shut it down completely.