topic Re: Backup slow in Operating System - HP-UX

Backup slow

SHANKU — Wed, 30 Jan 2002 14:01:17 GMT

Can any body help me in this case?.In my new L2000 server,backup is working very slow.It is taking 8 Hrs for 10 GB backup.I am using DDS3 for backup.pls help me

Re: Backup slow

David Navarro — Wed, 30 Jan 2002 14:14:55 GMT

Hi,
How are you doing backups? With tar, fbackup, OmniBack?
And what kind of disk do you have? Are configured in stripping, mirror, etc?
When you do that backup, users are working with your aplication?

David.

Re: Backup slow

James R. Ferguson — Wed, 30 Jan 2002 14:16:45 GMT

Hi:

You don't indicate what backup software you're using. If you are using 'fbackup', see the comments by myself and Bill Hassell in this thread:

http://forums.itrc.hp.com/cm/QuestionAnswer/1,,0xc5f35e938a10d6118ff40090279cd0f9,00.html

You should note the attachement I provided in my post therein, too.

Regards!

...JRF...

Re: Backup slow

Marcel Eken_2 — Wed, 30 Jan 2002 14:23:42 GMT

Hi Shanku,

I think the problem is that your dds is not in 'streaming mode' This means that the tape is stopped and started every time data must be written to tape.

What tool do you use to make the backups.

- If it is omniback you can increase the disk agents for your backup.

-If you use fbackup, try to increase the number or reading processes.

create a file and put in the followinf data:

blocksperrecord 16
records 16
checkpointfreq 256
readerprocesses 2 (maximum of 6)
maxretries 5
retrylimit 5000000
maxvoluses 100
chgvol /var/adm/fbackupfiles/chgvol
error /var/adm/fbackupfiles/error
filesperfsm 200

You can increase the reader processes to 4, and check if the drive stays in streaming mode. start fbackup with the -c config-file option.

Good luck,

Marcel Eken.

Re: Backup slow

Bill Hassell — Wed, 30 Jan 2002 18:44:15 GMT

It's also important that the system be somewhat quiet during the backup. If there are hundreds of file I/Os going on while trying to backup, the backup program cannot keep upp with the tape and it will be starved for data. This takes the tape out of streaming mode and if it happens often enough, the back will hours, even days to finsh a dozen or two Gigabytes.

Re: Backup slow

Darrell Allen — Wed, 30 Jan 2002 19:28:48 GMT

Hi,

I'm sure you'll get more answers once you provide the details about your backup.

Also, are you using a locally attached drive or are you backing up over the network?

Darrell

Re: Backup slow

SHANKU — Thu, 31 Jan 2002 07:36:09 GMT

Hi all
Sorry for not mentioning full details.
I am using fbackup and taking backup of filesystem in root VG for test purpose.ie local disk.Patch level is sept2001.
According to standards,DDS3 has to give 2.5MBPS.But here it hardly gives 300KBPS

Regards,
SHANKU

Re: Backup slow

Kenny Chau — Thu, 31 Jan 2002 08:10:36 GMT

Hi Shanku,

There maybe several reasons (as I guess):

1. Maybe the tape drive head problem, try to clean the tape drive head several times to see if it can help. If not, ask HP to replace a new tape drive.
2. If your directory contains many files, it will also take long time even the file sizes are small, ie. 1 10GB files will backup faster than 1000 10MB files.

Hope this helps.
Kenny.

Re: Backup slow

Steve Steel — Fri, 01 Feb 2002 15:00:54 GMT

Hi

I have seen this sort of thing when there were a lot of open files and 5 retries.When a file is open the fbackup will try it several times (with a delay)before going to the next one.

I would advise retuning the config file with.

maxretries 2
readerprocesses 4

And see if there is a difference.

fbackup works best when there are no users and
to see if there is a real tape problem you should try a backup when there are no users at
all such as in single user mode.

Steve Steel

Re: Backup slow

Frank Slootweg — Fri, 08 Feb 2002 09:09:17 GMT

Some additional comments:

DDS-3 Native Mode (i.e. uncompressed) *maximum* speed is 1 MegaByte/second, i.e. in order to get the 2.5 MB/second you mention, your data must be very compressable, and that is normally not the case on UNIX systems.

As the fbackup(1M) manual page mentions, for DDS the "blocksperrecord" parameter should be at least 64 (64 KiloByte).

If you have HP-UX 11.X, fbackup's "-v" option" will report how much it writes to tape, which might be much more than you expect. I.e. if you have many small files, the fbackup 'overhead' can be quite substantial.

As Steve mentioned, check the ("-v") log for retries.