B2D backup almost 50% slower then B2T

[NTP_Distributio]

We have tried to adjust the size of the backup files, as well as the number of backup files that can be used at once, and nothing seem to effect the backup time that much at all. 

Our full system backup, running over the weekend, is broken into two jobs because of the speed of the servers and the processes running (Exchange/Fax servers) and also the interfaces that are on the servers.  This backup is running as a Backup to Tape direct.  The two jobs take about 7-8 hours for theire processing including verify.  When I tried to setup part of the job as a B2D thinking that I could run that while the rest of it was doing the Backup to Tape, the backup took almost 3 hours longer.

We also run a differencial backup each night, and the backup is about 1/10 the size of the weekend backup, but takes 9 hours including verify.  This job is setup currently as a Backup to Disk and then Duplicate to Tape.

I am going to swap the two processes and do the Backup to Tape first, and then Duplicate it to Disk, and I am sure that it will take about 3 hours or so.

Any help on setup or configuration that may be the key to why the B2D is so slow, and the B2T is so much faster.

[NTP_Distributio]

After doing a bit more testing I found that the B2D took about 9 hours with Verify, and the B2T took 6 hours with Verify. 

Can someone please let me know what the ideal sizes would be for the B2D, I am currently using:

1GB file size, up to 100 files.

0 Reserve ( I had it at 10gb before)

Auto Detect Settings

4 Concurrent Sessions (Bumped up from the inital 1, did not appear to change anything)

From what I understood in the past, B2D should be much faster then direct B2T.

[Hywel_Mallett]

How are the disks your B2D folder is on configured? If you've got a fast tape drive, then you need fast disks, well configured to match the speed.

Also are the B2D folders on the same disk you're backing up?

[NTP_Distributio]

The current setup is a Backup server that has 4 10k 300GB SCSI320 drives in raid 5, and a system partition on 2 36GB drives.  The Tape Backup is a new HP MSL with dual tape drives. 

On the 870GB of available space, we have about 600GB setup for B2D, and another partition of about 270GB for files storage backup.

The servers that we are backing up and connected by either Gigabit or 100MB connections.  I know that a good part of the backup time is the Exchange backup since I can see that in the log files, but running the exact same backup to two different destinations (at different times of course), Tape and Disk, the Disk takes 9 hours for the Differental backup and the Tape only takes 6 hours. 

[Ken_Putnam]

B2D can REALLY chew up free space, and fragmentation can cause all kinds of slow-downs 

Check the fragmentation on the partition containing the B2D folder(s)

see also

http://support.veritas.com/docs/280072 

http://support.veritas.com/docs/284014

[NTP_Distributio]

We will try and run Disk keeper as well as make some adjustments to the Partition sizes to see if we can smooth things out.  We just recently created the partition so I would assume that fragmentation is not a problem, but we will see.

[Robert_Schmidt_]

Can someone please let me know what the ideal sizes would be for the B2D, I am currently using:

1GB file size, up to 100 files.
0 Reserve ( I had it at 10gb before)
Auto Detect Settings

Hi

If I'm reading your first post correctly, your B2D are presently once on weekend only, and full.

So, you would have a pretty good idea of size required (give or take for software compression on B2D).

Why not set the B2D file size close to that - create just one file, instead of hunderds of small.

And, depending on the service packs, use the pre-allocate option. - takes a LONG time the first time to create the file, but re-using after that helps avoid the fragmentation problem.

I have a set of 12 B2D files like this - 6 days a week, 2 complete sets.

[NTP_Distributio]

We run a Differential Backup Monday-Thursday, and then a Full backup on Saturday.  We were using the B2D on the Differentials only, becuase the Full Backup appears to be ok at ~9 hours.

Our backup of Differential is about 50-60GB on average each night.  If I was to create a single file for the backup, how can I make it large enough that it can hold a large change in data, and still allow all 4 Differential backups without overwrite.  I would like to be able to keep as close to 2 weeks as possible, but If the back up gets larger then the 60GB then it may only be good for about 6-7 backups. 

What you would recommend is creating a single 100GB file and using that for Monday, then another for Tuesday, etc?  We have 506GB available for this, so it would give me a bit over one week.

Would using the Preallocation option speed things up, since that is the overall objective is speed?

[Robert_Schmidt_]

We seem to get a lot of "software" compression with B2D - of course, I realise that depends on the type of data being backed up.

But, as an example - I have a set of 40Gb B2D files. The 'media' tab shows roughly 31Gb to 35Gb used. Remember, you don't see anything in the 'Compression Ratio' column for B2D.

But - the job log shows I'm backing up roughly 100Gb each night - into that 40Gb B2D file.

So, set the max size on  your inc. B2D folder to 40Gb as a try. If BE needs more (unlikely), it will just create another. You sound like you have enough disk space to play with for at least one day to try this out. Once you see how much of the B2D file is being used, maybe you can reduce the max. size. Similarly, if you find your data is growing and BE creates 2 files for one night, just increase the size by 5Gb or so.

Preallocate - definitely won't speed things up the first time - takes a while to create the whole file. But would hope you would see an improvement next time through the cycle.