BackupExec causes horrendous fragmentation

[Ross_Smith]

I am seeing incredible fragmentation on the drive we use to store our BackupToDisk files. I'm posting more details below, but if you are using B2D, could you please check the fragmentation level for me and let me know if you are also having this problem.

We have a 570Gb NAS device used as the main target for all of our backups. This device has been in use for approximately 6 months and is used almost exclusively for B2D backups.

After numerous problems with BackupExec, I happened to run a defrag analysis on this device, with the following results: http://www.averysilly.com/Defrag%20report.jpg.

Even after deleting 350Gb of B2D files, we are still getting 99% fragmentation reported with files scattered across the entire disk, and with a 1Gb b2d file in as many as 40,000 fragments.

I am still speaking with Veritas, we've no clear idea what caused this, but on at least one occasion I have set BackupExec to allow concurrent operations to this B2D device, and we suspect this may be the cause of this fragmentation.

We are defragmenting this device today to see if it fixes our problems, but I would be very interested to know if anyone else is seeing similar effects on their B2D devices?

RossSubject line updated 20/6/05 by:
Ross Smith

[H_Vincent_Latus]

I don't know what is going on then with my backup array.

I am backing up database log files here:

BE 10d From remote server with agent to backup server with Direct attached Ultrium 2 tape drive. The network is Gb ethernet

Time = 00:03:53, Size = 14,460MB, MB/Minute = 3,551

BE 10d From remote server with agent to backup server with Direct attached storage array. 9 Disk RAID 6 ADG, the network is Gb ethernet

Time = 01:32:00, Size = 14,404MB, MB/Minute = 149

The only thing I can think of is that I run multiple jobs to the drive array at the same time, and when the tape jobs runs they happen sequentially. Is that what is killing my performance?

Vin

[Ross_Smith_2]

Multiple jobs will definately slow it down - you're adding additional seek time to every bit of data you write, this could have a huge effect on performance.

Try running just a single test job and let me know what speeds you see.

[H_Vincent_Latus]

Did another test with only one job running, it's better, but still very poor.

Time = 0:45:54 Size = 14,299 MB/Min = 297

[herve_lequippe]

To all participant in this Thread.

Symantec is pleased to announce that it has released Hot Fix 27 for Backup Exec 10d.

This Hot fix fixes the fragmentation issue some of you have been experiencing.

The fix is done in a similar way as the one that Ross Smith and some others have been testing with the Backup Exec 11 Beta. By Pre allocating space on the disk for the B2D files, we have been able to remove the fragmentation you are encountering

If you experience fragmentation with your Backup to Disk, I encourage you to download more information here

http://seer.support.veritas.com/docs/283264.htm

Make sure to read the document that comes with this Hotfix. Also note that this Hotfix will NOT correct existing fragmented disks

HERVE LEQUIPPE
Sr. Product Manager EMEA
herve_lequippe@symantec.com

[Ross_Smith_2]

I can confirm that this does indeed solve this problem. After several weeks of testing and 500GB of backups I have zero fragmentation on my main backup drive. There's not even a single fragment present.

The downside of course is that there's no easy way to defrag an already fragmented drive.

I've found defrag software takes too long on a large volume to be effective, however with all our NAS backups duplicated to tape it was an easy decision for us to wipe the NAS device and start afresh, relying on our tape backups for a week or so.

Ross

[Joop_Idema]

I can also confirm that this solves the fragmentation problem, but it creates a new one.
The first time a new B2D file is created this takes a long time. For instance, a 5GB file takes about 20 minutes to create.
Of course this is only a problem during the first time such a backup is started, because if you overwrite your backup, the B2D file it is not created again.

Perhaps there is a way to speed this up in a future hotfix?

[Jason_Smith]

I'm looking for ways to speed up the preallocation. Jobs that must create the .bkf files a very long time to run, almost double. Once i've got the appropriate number of .bkf files for my backup retention i shouldn't have that may issues, but i'd love to force backup exec to create the files manually.

Another thought is copying existing files. Has anyone had any luck copying the .bkf files and renaming to a new bumber and importing them somehow?

[Lars_Lange]

I too can verify that the fragmentation problem finally is solved. But this issue has taken Veritas almost one year to solve :( That is too long Veritas.

To joop - regarding creating the BTK files.
We use 1 gb files instead. Specially because we run incremental backup on the B2D jobs, so we don't waste too much space on nothing.

/Lars

[Ross_Smith_2]

Veritas also recommend a maximum of 1/2GB for any network backups. We're running 1GB bkf files here and I haven't noticed any performance problems but have to admit I've not really been watching it closely either.

[Mike_Lee_2]

There is a patch for 10d, but how about 10.1? Is this resolved in 10.1?

Thanks

[Mike_Lee_2]

Is this resolved in 10.1 as well?

[herve_lequippe]

To clarify this :

10.1 and 10d are the exact same version.

Full support for this feature (without the need for an Hotfix) will be in Backup Exec V11d coming out in Q4 2006

HERVE LEQUIPPE
Sr. Product Manager
Symantec Corp

[bamsuharto]

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