Zero'ed files?

[Tim Jones]

Hello all,

I have had an issue on a production system backup - the synopsis as follows:

1. Backup server running Backup Exec would not update to 9.1 SP1 - would
keep on blue screening when I tried to do the install. Went through with
support and got it installed.

2. Production oracle server failed (apparently through a combination of the
cold backup running while McAfee was running).

3. Needed to do restore of system, however on restart (a job had hung, and I
figured I'd start fresh with the backup) the system blue screened -
non-specific 0x0000007E error.

4. Removed the external drive array and tape unit during troubleshooting and
the system started up OK.

5. When I started with either the external drive array or tape unit on it
started up OK, but not with both.

6. Started up the drive array, however all disks were marked as DDD (Defunct
or Dead drive) - this contained all the backup files due to problems with
the tape backup.

7. Rebuilt the array and the files showed up.

8. Tried to restore, and catalogue the files, however these failed.

9. Upon inspection, the files were completely empty. I can write other files
to the drive array so it is not stuffed. The array is still rebuilding.

Does anyone have any idea on how to recover from this, or why this would
happen?

I don't think it's the drive rebuilding, as it is showing as OK. I don't see
what else could have done it.

Any ideas? Feeling sick having to explain this to the business.

Thanks and regards,

Tim Jones

 

[Phillip Windell]

Files that are "0 byted" I don't think are recoverable without getting them
from another source like a Tape. I have seen this happen in a hardware
failure (which wouldn't be your fault).

I could be mistaken, but I believe what happens when a file is written to a
drive is that first an empty file is created and assigned a name. I think an
entry is created in the File Allocation Table at that point (but unsure),
then the actual data is copied to this new file. If a failure happens just
before the data is finished copying but after the file is create the files
obviously would contain nothing. This could be what happened with the BSOD.

With RAID arrays accompanied by a SCSI Tape drive I have run into issue
during setup on some HP equipment where it kept treating the Tape Drive as
SCSI Device 0 and expecting it to be the "C" drive. So I always had to setup
the RAID Array first with the Tape drive unpluged and then plug the Tape
Drive in afterwards. This seemed to happen even when the "jumpers" on the
hardware was set properly.

 

[Tim Jones]

Files that are "0 byted" I don't think are recoverable without getting them
from another source like a Tape. I have seen this happen in a hardware
failure (which wouldn't be your fault).

I could be mistaken, but I believe what happens when a file is written to a
drive is that first an empty file is created and assigned a name. I think an
entry is created in the File Allocation Table at that point (but unsure),
then the actual data is copied to this new file. If a failure happens just
before the data is finished copying but after the file is create the files
obviously would contain nothing. This could be what happened with the BSOD.

With RAID arrays accompanied by a SCSI Tape drive I have run into issue
during setup on some HP equipment where it kept treating the Tape Drive as
SCSI Device 0 and expecting it to be the "C" drive. So I always had to setup
the RAID Array first with the Tape drive unpluged and then plug the Tape
Drive in afterwards. This seemed to happen even when the "jumpers" on the
hardware was set properly.

Thanks for the response Philip.

Tim