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Backups taking too long

Beth_2
Occasional Visitor

Backups taking too long

Hello,

We are trying to backup about 30 GB's of data with a DLT8000 tape drive and the problem is that it is now taking about 25-30 hours to complete. This is on a NT 4.0 box, using Seagate Backup Exec 7.0 (verify is off), with DLT IV tapes and an Adaptec SCSI card. This started about a month ago and we are unable to figure out why it is happening. Any suggestions would be appreciated.

Thanks in advance for your help!

Beth
7 REPLIES
paul courry
Honored Contributor

Re: Backups taking too long

How many errors are you getting during the backup? This could be why it is taking so long. I've seen causes range from bad cables to bad media to bus contention to an overloaded CPU to god knows what.
Thierry Poels_1
Honored Contributor

Re: Backups taking too long

Hi,
30 hours for 30GB on DLT?? Maybe you should upgrade to floppy disks ;)
now serious, I suppose you're trying to backup local disks on a local DLT, so we can exclude network.
possibilities:
- DLT failure? try reading some DLT's; does that seem to work within a normal timeframe.
- changes in hardware since the problem occurs?
- hard disk problems? keeps on retrying on bad blocks?
- can you follow processing in the logfile when backup is busy? is processing slow overall or only for some files (large files, files in use,...)
- bad scsi cable / terminator?
and like Paul said : many others ....
good luck,
Thierry.
All unix flavours are exactly the same . . . . . . . . . . for end users anyway.
Alexander M. Ermes
Honored Contributor

Re: Backups taking too long

Hi there.
First :
Do you have any other devices on the SCSI interface, where you have hooked the DLT ?
The DLT should have an interface of its own.
If you have the disks on the same inetrface, the DLT may not go into streaming mode, that means, it will wind and reinwd for any access.
Second :
You should not use software compression on these devices, because they have an internal
processor to do so.
Hope, i could help.
Rgds
Alexander M. Ermes
.. and all these memories are going to vanish like tears in the rain! final words from Rutger Hauer in "Blade Runner"
Alexander M. Ermes
Honored Contributor

Re: Backups taking too long

Sorry,
one more issue.
The interface should be FWD SCSI
( Fast Wide Differential ).
Rgds
Alexander M. Ermes
.. and all these memories are going to vanish like tears in the rain! final words from Rutger Hauer in "Blade Runner"
paul courry
Honored Contributor

Re: Backups taking too long

That FWD SCSI must also be an HSC bus, DLT8000's don't work on HP-PB.
Keith Foradori
Occasional Visitor

Re: Backups taking too long

Virus software can slow down the Backup considerably. If you have installed or updated virus software, try using a before-and-after script to turn off/on scanning during the job.
Eric de Lange_2
Respected Contributor

Re: Backups taking too long

hello Beth,

At http://www.hp.com/cposupport/information_storage/software/pat.exe.html you can download the performance Assesment Tool. It runs a series of tests on your system to see what sort of throughput your configuration is capable of.

If this returns normal throughput's (5MB/sec or so) then you will need to investigate the SCSI/tape side of the configuration.

If PAT returns abnormally low throughput's as well, you know that there is something on your system slowing the DLT down.

Also, make sure that BackupExec has the latest patches installed and that your backups are using a decent blocksize (32K or so). This can be configured in BackupExec itself.

Hope this helps you on your way !

Cal.