MD5 digest errors

[urza311]

I have a Windows station (Pentium-4 2.6GHz with 1G RAM, Windows XP with SP2 and all latest updates) running Retrospect Professional (7.5.320 with driver 7.5.6.105). I added a 5-user remote pack to it so it could remotely backup 7 other workstations here. What it does is backs up their data into individual File Backups on the internal hard drive of this station then, after that, Retrospect backs up all the data on this machine (including those files) to a Sony SDX-570V (AIT2 Turbo). The File Backups range from 192M to 1539M as of this writing. Clients are connected either by 100BaseT or Gigabit Ethernet, and are running client 7.5.116 under Windows XP Professional SP2.

 

On-and-off, I'll get a verification error involving these File Backups. Sometimes the error occurs when it's doing the backup of a remote client, and other times it'll be when it's backing up one of these File Backups onto the tape. It's not always the same client or File Backup set that has the error, and if it fails on any given night, odds are it won't fail the subsequent night.

 

Any idea why this happens? The other idea I had was, instead of backing up the remote clients to File Backups, maybe I could run those as Duplications instead -- back up the contents of their data into individual folders on the internal hard drive of this station, then have Retrospect backup those folders to the tape... since the error only occurs when dealing with these File Backups (.RBC files), maybe this would circumvent the issue.

 

Below I've excerpted my operations log showing the error. Any feedback would be appreciated... thanks.

 

 

- 8/30/2006 3:32:14 AM: Copying swiss on SwissArmyKnife (C:)

8/30/2006 4:20:50 AM: Snapshot stored, 2,301 KB

8/30/2006 4:21:00 AM: Comparing swiss on SwissArmyKnife (C:)

File "C:\Documents and Settings\swiss\My Documents\Retrospect Catalog Files\r-Busse.rbf": didn't compare

An error occurred during the verification step. The MD5 digest for the file "C:\Documents and Settings\swiss\My Documents\Retrospect Catalog Files\r-Busse.rbf" did not match, error -1129 (MD5 digest mismatch)

8/30/2006 5:07:03 AM: 2 execution errors

Completed: 3942 files, 7.7 GB

Performance: 167.6 MB/minute (163.2 copy, 172.3 compare)

Duration: 01:35:03 (00:01:06 idle/loading/preparing)

[nekr0phage]

Hi Chris,

 

A typical disk-to-disk-to-tape scenario has all source backed up to a disk backup set, then performs snapshot transfers to tape. The disk backup set allows you to use grooming, which provides simple data management for the data stored on the backup machine, and transfering snapshots allows you to restore directly from tape to whatever machine you want, rather than having to restore a file backup set, then perform a second restore of the data you need. Here is a link to a whitepaper for d2d2t info: http://kb.dantz.com/article.asp?article=8020&p=2

 

Are you using encryption with these file backup sets?

[urza311]

What I have been doing is a recycle disk-to-disk backup every night, and then the tape backup grabs the entire folder containing all 7 File Backups. This is actually pretty wasteful of the tape space because probably 75% of the data on one of these remotes doesn't change, yet the tape has to copy the entire File Backup because it's new. Because of this, I'm looking at doing duplicates instead... if I do this and, for example, grab a particular picture file from a remote client but that picture file doesn't change for a week, will the nightly tape backup skip over that file during a normal backup if it had grabbed that same file the night before? In a comparison of the date/time/checksum of the file, it would remain identical to the version from the night before, even if it is technically a whole new copy every night.

 

As for encryption -- no, I don't believe I'm using any encryption. I certainly didn't enable anything beyond default settings. I looked around and didn't see any kind of encryption setting enabled... can you tell me specifically what I'm supposed to look for? And if it's disabled by default, I can pretty much guarantee it's not on... I usually don't encrypt anything in backups. I even make sure there's no password on any of the clients... the only copies of Retrospect that'd be able to tie into a client here are controlled by me, so I'm not worried about security in-house.

 

Thanks for your time!

[nekr0phage]

Hi Chris,

 

You're right, the file backup set will be wasteful of tape space as well as inconvenient for restore. Again, I think you should consider a disk backup set rather than duplicates. A disk backup set will allow matching from the source disk, so you won't have to copy all your data every time you run the backup. Using the transfer snapshots feature, it also allows you to match data between the disk backup and the tape backup, so only new files will need to be copied to tape. Also, using an intermediate backup set will allow you to store snapshots of your source machines. You will need snapshots if you ever need to do a full system restore on one of your machines.

[urza311]

I read up on the file backup solution you mentioned... that makes sense, although I have a small snag. I currently have 7 clients and 14 separate volumes (on average, two folders on each client -- I only backup some data files, not the full client volume) that need to be backed up to this system. I have only one internal hard drive in this unit now, and that's got the system and everything on it... I can't use that drive as the target because it contains the system and applications and such. However, I think I can scrounge up a 20G hard drive and install it as a second drive, then use that as the target. Can I write a single backup script that picks all 14 of these sources and backs them all up to a single file backup target? Will it just make 14 individual folders on the target drive, one for each "volume" it's being asked to backup?

 

In the meantime, I did go ahead and switch to using duplication instead of targeting file backups. This will make restoring things a lot easier... but now I'm getting other errors.

 

File "C:\Documents and Settings\aballard\Local Settings\Application Data\Microsoft\Outlook\annette.pst": didn't compare

File "C:\Documents and Settings\ballardp\My Documents\DSCF2155.JPG": didn't compare

File "C:\Documents and Settings\margeb\Local Settings\Application Data\Microsoft\Outlook\mbishop.pst": didn't compare

 

One night it will successfully backup one of these files, and another night it'll flag it with this error. I'm still getting a copy of the file, but it does say it's not verifying. I've opened a few of these items that it claims are not verifying, and they seem okay (even that picture). I can say for sure that these files are NOT open on the client side -- they always shut down all their applications before leaving for the night.

 

Since my initial posting, I've updated to Retrospect 7.5.324, but still get those error messages. I'm not having any read/write problems with the internal hard drive as far as I know (at least, nothing I've been alerted two, and this system has been running fine for like six months). I've also looked on our gigabit switch logs and see no network errors. So I'm not sure why it's failing to verify these files sometimes.

 

Anyone got any ideas? Should I be concerned?

[Mayoff]

If these files are comparing correctly when using thorough verification, then you are seeing a cosmetic bug we discovered recently with media verification. The files themselves are okay if Thorough verify isn't reporting an error also.