Backup Exec 2010 R2 job not fitting on single tape.

[ypadmin11]

Hi all,

I am having some odd problems with the backup exec software we have installed. This can be a little complicated to explain so please bare with me :)

We do a complete full backup of all the data to tape everyday. I manually change the tape everyday after the backup is done. We have tapes for every week of the month, so for example we have Monday 1, Monday 2, Tuesday 1, Tuesday 2 etc up till week 4. Than we take a full backup on the last day of the month and keep it separately.

Now the problem is that when we first started this schedule we started using brand new tapes. On Wednesday 2 and Monday 3 the backup for some reason didn't fit on the tape and asked for another for it to be able to continue. At the time I checked the settings and checked the backup log to see if any changes were made to the job but since nothing changes I ignored the problem, changed the tape and the backup worked fine again.

I tried re-formatting the tapes with long erase and re-tried the jobs on those tapes again when their time came the month after. Again the backup didn't fit on them and again nothing was changed. After this I thought that maybe the problem was that the tapes are faulty so I exchanged them with new ones. Now the really weird part is that the backup again did not fit on a single tape last night on the new tape that replaced Wednesday 2! Now I checked again and nothing has changed since and don't know what to think or even how to troubleshoot this problem, that is why I'm posting this message here in the hope that someone has encountered such a problem and maybe can shed some light on what is happening.

Any information regarding this would be most appreciated. Thanks everyone in advance.

[CraigV]

Hi there,

What sort of compression are you getting on those tapes? What size are they?

Has your data grown in size during your backup runs?

Thanks!

[pkh]

On the Media tab, click on one of the tape that is full and check the tape statistics below.  See how many bytes are written and what is the capacity of the tape.

It could be that you are compressing compressed files like movie files and zipped files and the final file size is greater than the original file size.

[ypadmin11]

Hi CraigV,

Thanks for the reply.

The tapes are Ultrium 3 400G / 800G.

The data hasn't grown except for a few mbs which shouldn't affect it. The average backup size is of 650G.

I checked the compression we are getting and it varies. Mostly it's 1.7:1 but sometimes last time it didn't fit on the tape it's 1:1. Is there a way to make the compression constant? Maybe that is what is causing the backup to not fit.

[ypadmin11]

Hi pkh,

Thanks for the reply.

I have attached a screenshot with the statistics of the tape. The compression ratio is 1:1 and it varies greatly every day for some reason. We always backup the same data so this seems strange. Is there a way to stabilise this?

Also attached is a screenshot of the errors tab, is it normal to have so many errors?

[Ken_Putnam]

you will almost never get 2:1 compression, which is required to fit 800GB on those tapes.  Your reported ration of 1.7:1 is actually quite good.  I normally figure about 1.2-1.3:1 as a SWAG when setting up a new backup job

See  http://www.symantec.com/docs/TECH6076

Backups fail to get double the amount of the native capacity ...
 

[teiva-boy]

Is your overwrite period configured correctly?  

[pkh]

For a tape with just 4 mounts, it has a lot of soft write errors.  Check your other new tapes.  If they also show a lot of write errors, then it is highly likely that your tape drive is faulty.  You should run the manufacturer's drive diagnostics against this drive.  Make sure that you stopped all the BE services first and select the write test.

If you are positive that you are backing up the same data, then your compression ratio should remain roughtly the same.  It should not vary a lot.  If you are using hardware compression, try changing to software compression and see how it goes.

[ypadmin11]

Hi pkh,

I will try out software compression and see how it goes and yes I am positive that the data is exactly the same.

A question however, does software compression take more time or has any disadvantages compared to hardware compression?

Thanks in advance.

[CraigV]

Hardware compression uses the capabilities of your drive...software compression uses resources from your server, meaning there is always the chance it will cause a slowdown on your system...

[Ken_Putnam]

To add to Craig's answer

if you use SW compression, you can only restore using BackupExec

if you use HW compression, you can use any software you wish (as long as it supports MTF - Microsoft Tape Format, including NTBackup) for files anyway. Database agents will normally need BackupExec

But to repeat what I mentioned above

You will almost never get 2:1 compression, which is required to fit 800GB on those tapes.  Your reported ration of 1.7:1 is actually quite good.  I normally figure about 1.2-1.3:1 as a SWAG when setting up a new backup job

See  http://www.symantec.com/docs/TECH6076

Backups fail to get double the amount of the native capacity ...

[CraigV]

Interesting one Ken, didn't know that.

It explains why I restored data backed up in 2007 using ARCserve 11.5...did that with BE 2010 R2. It took 2 hours to restore 1.6GB, but it completed successfully!

[ypadmin11]

Thanks both Craig and Ken.

I tried as you suggested. I tried making the compression software. It is working much faster than hardware used to do however the problem is not yet resolved. I tried the same job a few times and occasionally I get the same problem again where the job doesn't fit on a single tape. I am positive that we are backing the same data since this is just one job.

Also tried an earlier suggestion about running some diagnostics on the tape drive to see if it's faulty or not but unfortunately I haven't had any luck since the manufacturer tools are not finding the device. The drive is a Quantum drive, if you can direct me to some 3rd party tools that might help me it would be greatly appreciated.

Thanks in advance.

[pkh]

Before you run the manufacturer's diagnostic utility, you must stop all the BE services.

[ypadmin11]

Yes I did that and tried installing the manufacturer's original driver and everything but still it's giving me an error.

[pkh]

If the manufacturer's diagnostic utility has problems detecting the drive, then it is highly probable that there is a hardware problem with your tape drive.  You should get your vendor to take a look at it.