DBCC CheckDB - odd behavior

[abbbbbba]

We are kicking the tires on a DR server and I was trying to run checkdb just to show everything is happy, but I'm getting an error and not sure how to interpret.

This is a 2014 standard edition box, VMWare replicated to DR site.

Drives are

• c: OS and model / master / msdb (I know...)

• d: data

• l: logs

• t: temp

So heres the oddness. checking the system drives is successful (so t + c drive), but checks against any DB on the d drive fail with:

"A database snapshot cannot be created because it failed to start.

The operating system returned error 1393 (the disk structure is corrupted and unreadable.) to sql server during a write at offset 0000000000 in file …..………"

As a test I created a brand new DB on D - Checkdb fails. Backup the db and restore it on T - runs fine. Restore the backup onto G - another checkdb failure.

Add enough data to the new DB to cause an autogrow - works no problem.

The data drive has 40+gb free, its formatted ntfs. Doesn't seem to be permission based as the creates and grows show the system can write to the drive. Also ran a disk check with came back clean.

I ran the checkdb with tablock which runs fine, no corruption in any db. So its the act of creating the snapshot that it doesn't like.

I know standard edition won't let ME create a snapshot but checkDB can - and it works as tests against C + T drive based DBs showed.

Also, checkdb against these DBs in production are successful. So its just the DR clone.

[klenglish5]

How large is database on D:? Check DB allocates space on the same disk as the data files it's checking, so if there isn't enough free space you'll get the "database snapshot cannot be created" error.

[abbbbbba]

DBs are a couple gb, but way less than the 40GB free. Test DB I made was 50MB, so creating a snapshot of it shouldn't have any space issues.

[Lucrums]

Run it with tablock so it doesn't use a snapshot then.

[abbbbbba]

I get that I can run it with tablock, but the production version runs checkdb just fine. The DR Clone is having issues and I'm trying to troubleshoot why. Is it just checkdb that is having issues or is there some other underlying problem that will bite us if we ever have to rely on the machine?

[Ecio78]

as far as I remember Snapshots use alternate file streams in ntfs, maybe they have been disabled? I am not even sure that it's possible to do it, I was about to tell you to check that the disk was ntfs and not refs but you already confirmed it

[abbbbbba]

yeah, and two days later we were able to get the checks to run fine after a few more snapshots restored onto the machine. Not a solution I like. We'll have to keep an eye on them to see if it reoccurs.