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Brbackup with remash/dd too long

Bono_1
Occasional Visitor

Brbackup with remash/dd too long

Hello,

we are trying to do a brbackup via network. Before it was working when the database war 150 Go. Now the database is about 200 Go and it doesn't work anymore.
The initial parameters for the remsh/dd was:
dd_flags = "obs=512k bs=512k"
dd_in_flags = "ibs=512k bs=512k"
copy_out_cmd = "dd bs=512k of=$"
copy_in_cmd = "dd bs=512k if=$"
with those parameters, the brbackup hangs at the end.

We've tried (with SAP recommandations):
dd_flags = "obs=256k bs=256k"
dd_in_flags = "ibs=256k bs=256k"
copy_out_cmd = "dd ibs=256k obs=256k of=$"
copy_in_cmd = "dd ibs=256k obs=256k of=$"
and
dd_flags = "ibs=512k obs=32k"
dd_in_flags = "ibs=32k obs=512k"
copy_out_cmd = "dd ibs=32k obs=512k of=$"
copy_in_cmd = "dd ibs=512k obs=32k if=$"
With those parameters the estimated timeframe for the brbackup is more than 8 hours!!!

Thanks for your help.
9 REPLIES
Volker Borowski
Honored Contributor

Re: Brbackup with remash/dd too long

Hi Bono,

Backup: 200GB/8hours = 25GB/hour ~ 420MB/Min
LAN: 100MBit / sec = 750 MB / Min

Real Life: ~ 1GB in 2 Min in a 100MBit/sec network-copy
I think you 8 hours is reasonable if your connection is 100MBit.
Validate your KB/sec throughput using an ftp transfer.
Is you network switched ?
What else runs concurrently over the same routers. May you meet another backup on the LAN in the last section of your backup-time-frame.

What is your tape hardware ? LTO ?
How long did it take you to backup the 150GGB ?

You need to know warp-speed first, before you can say if you are slow.
Hope this helps
Volker
Bono_1
Occasional Visitor

Re: Brbackup with remash/dd too long

Hi Volker,

thank you for responding me.
For the backup we have a LAN 1 Go and with this network we also backup a 120 Go database in 1h20 without any problem.
Before the database refresh, this database was 150 Go and it took between 1h40 and 2h to do the backup.

This night, I've tried another time thoses parameters:
dd_flags = "obs=512k bs=512k"
dd_in_flags = "ibs=512k bs=512k"
copy_out_cmd = "dd bs=512k of=$"
copy_in_cmd = "dd bs=512k if=$"
and the brbackup lasted 1h40 but it hangs at the end! We have the kill the dd process to make the brbackup end and SAP start.

Thanks in advance.
Patricia Bono.
Volker Borowski
Honored Contributor

Re: Brbackup with remash/dd too long

Nice LAN Hardware :-)

How do you start the backup ?
Can you attach a logfile of the run ?

If not, can you please check Version and
patchlevel of brbackup with "brbackup -V".
May be you need to patch it.

Version 6.20 PL 120 is current

Thanks
Volker
Brian Crabtree
Honored Contributor

Re: Brbackup with remash/dd too long

Ermmm. Why are you using dd? The only reason I can think of to use dd would be for raw filesystems.

Thanks,

Brian
A. Clay Stephenson
Acclaimed Contributor

Re: Brbackup with remash/dd too long

The first thing that I see that is strange is that you are specifying both bs AND ibs or obs. If you specify bs, you should only specify bs, because bs sets both ibs and obs. Moreover, "bs=512k" is better than the seemingly equivalent "ibs=512k obs=512k" because the latter version requires a copy from the input to the output buffer while the former uses only one buffer for both so that no copy is required.
If it ain't broke, I can fix that.
Bono_1
Occasional Visitor

Re: Brbackup with remash/dd too long

Hi, thans for your answers,

I've already changed the brttols, now I'm using 6.20 level 120.

The backup is started in crontab:
su - oraqs1 -c "brbackup -i force -v $label -n 1 -c force"
su - oraqs1 -c "brbackup -v $label -p $INIT -c force"

I attach the file INIT ans a logfile of a run with dd blocks=512k. In the logfile you can see the databse startup at 7h14 and after the command:
BR202I Saving reorg_log

BR203I to /dev/rmt/1mn ...

BR202I Saving /oracle/QS1/sapbackup/bdmpqoxv.afp

BR203I to /dev/rmt/1mn ...

BR202I Saving /oracle/QS1/sapbackup/backQS1.log

BR203I to /dev/rmt/1mn ...

we have to kill the dd process to make the brbackup end.



Why I'm using dd? Because with brbckup it's cpio and dd and we've already used dd, I don't know why.



This evening, I'll try those parameters:
dd_flags = " bs=256k"

dd_in_flags = " bs=256k"

copy_out_cmd = "dd bs=5256k of=$"

copy_in_cmd = "dd bs=256k if=$"


Thanks for your help.
Patricia Bono.
Volker Borowski
Honored Contributor

Re: Brbackup with remash/dd too long

Hello once more,

Try:

copy_out_cmd="dd ibs=64k obs=256k of=$"
This is the command that writes to the tape. It should therefore have an "obs" that is adjusted to the blocksize of the tape_device.
"ibs" is the size that is read from the network.

dd_flags="ibs=256k obs=64k"
This are the flags that read the database-files and write to the backup device. You usually want to use a bigger "obs" for local tapes to keep it streaming, but because you backup to "backup_dev_type=pipe" you should use a "obs"-blocksize that is suitable for the network.

Since the configurationfiles and the protokollfiles are written at the end with cpio, (no matter how "tape_copy_cmd" is set), you need to adjust "cpio_flags" as well to fit the "ibs" from the command reading from the network". So in case you have the network part to use 64k, you might try
cpio_flags="-ov -C 65535"

The *in* parameters (copy_in_cmd, dd_in_flags, cpio_in_flags) need to be set the other way round. If this does not help, try to reduce the network part to 32k.
This might help for reference:
http://help.sap.com/sapdocu/core/47x200/HELPDATA/EN/0d/d309e84a0c11d182b80000e829fbfe/frameset.htm

If your tape is DLT, 64k "obs" to the tape might be better, because the networkstream might be too slow. If it is LTO, I can't say (never used one accross the LAN).

Good luck
Volker
Brian Crabtree
Honored Contributor

Re: Brbackup with remash/dd too long

Bono,

The brtools are nice, however they are not the only way you can backup the database. You can go with rman directly, and get the backup with that utility, you can write your own script to put the database in backup mode and backup to tape, or write your own that will copy the individual datafiles to disk. Either option is possible.

Thanks,

Brian
Bono_1
Occasional Visitor

Re: Brbackup with remash/dd too long

This night, I've used
dd_flags = " bs=256k"
dd_in_flags = " bs=256k"
copy_out_cmd = "dd bs=5256k of=$"
copy_in_cmd = "dd bs=256k if=$"

and it works!!! The brbackup was made in 2h40 without any problem.

Thanks everyone for your help, now I've understood the dd parameters!

Patricia Bono.