Recently I saw in our SQL Server logs that a snapshot could not be taken at the specific time and he retried it later on. During that timespan we had a huge performance problem. Besides the SQL Server we have some files there as well, this will be changed next week but still I am interested what a snapshot does to a running system.
As far as I understand VMWare let SQL Server freeze the DB and gives him an amount of time to clear the cache and complete running requests. If this doesn't happen in the given time WMWare will try to take a snapshot again later on. We experience performance loss for a timespan up to 30 minutes while the database backup only takes up to 120 seconds according to SQL Log.
What are the steps that VMware and SQL Server do? Also when are the files captured?
Unfortunately I don't have vsphere access since it's not hosted by us, so I can't check logs there.
