Sybase backup server performance under HP-UX 11i

[Raul Aviles]

Hi, we have a RP8400 server with 8 processors, 8gb of ram. We are running HP-UX 11i. Out database is Sybase 12.0.
The server is normally 40% idle of processor usage but when we run the backup process thru Sybase Backup Server idle time goes to 0% and online application that uses Sybase have a really bad response time. How can we make that Sybase Backup Server don´t steal resources to online applications?
Actually we have assigned a higher nice value to the backup process, that means a lower priority than dataserver process and application process.

Thanks in advan

[Michael Schulte zur Sur]

Hi,

how many online engines and backup server processes have you got?

greetings,

Michael

[Bernhard Mueller]

Raul,

using nice is actually the way to go and keep the backupserver process out of the way as much as possible, you may wish to even use a "radical" nice value such as 19 if it impair crucial performance.

Now, for your understanding: Do not expect to always have an idle value of 30 or 20 percent by starting the backupserver using a nice value. Actually, the nice value comes into play *only* when the system is at 0% idle! Then nice says: "you first my friend"

If there are CPU resources available *why* shouldn't they be used? You paid enough money for them, so they should do some work, eh? ;-)

Acutally, when you test this (gzip is a good one for doing this!) you can see in "top" that for a given process such as zipping the kernel and unzipping, it you will always use about the same TIME (i.e. CPU TIME) however total execution duration (i.e. real time) will be much longer, but *only* when the system has other processes running requiring all avail CPU...

E.g. with 8 CPUs staring 9 gzips at the same time but with different nice values where all gzips will be compressing a copy of the same big file will show you what I mean.

Regards,
Bernhard

[Bernhard Mueller]

Now you tried it with nice and still are not satisfied?

Then you should consider using PRM (Process Ressource Manager) this helps you reserve resources (incl. memory) for critical processes.

http://docs.hp.com/hpux/onlinedocs/B8733-90009/B8733-90009.html

Regards,
Bernhard

[ALPER ONEY]

Hi,
Could you post the output of the following command?
cat $SYBASE/$SYBASE_ASE/install/RUN_

Regards.
ALPER ONEY
I.S.E TAKASBANK INC

[Raul Aviles]

Hi, everybody
First I have to tell you that we really have 6 processor working and 2 processor in ICOD mode (it means not used but can be used in the future on demand).
Next my answers:
Michael : 5 processors are assigned to Sybase and there area 5 engines. Every two hours we run 3 backup process.
Bernhard : We agree that is ok that we used 100% of all processor . That is wright. But the problem is that the response time of online request is bad when we run the backup process. As I told you the nice value of backup process is 30 and nice value of online application is 20, but it seems that backup process is stealing resources from online application. How can we control this?

Next I post the output of the following command?
cat $SYBASE/$SYBASE_ASE/install/RUN_

sybase>$cat RUN_SYBASE_back
#!/bin/sh
#
# Backup Server name: SYBASE_back
# Error log path: /sybase12/ASE-12_0/install/SYBASE_back.log
# Maximum number of network connections: 25
# Maximum number of server connections: 20
# Multibuf executable path: /sybase12/ASE-12_0/bin/sybmultbuf
#
/sybase12/ASE-12_0/bin/backupserver \
-SSYBASE_back \
-e/sybase12/ASE-12_0/install/SYBASE_back.log \
-N25 \
-C20 \
-M/sybase12/ASE-12_0/bin/sybmultbuf \
-m1024 \
sybase>$

Regards

[Bernhard Mueller]

Raul

as mentioned, with nice you can run it at 39 instead of 30, that is all you can do.

Since I understand this is am important production server, it may be actully worth spending 10k$ and use PRM. That should solve your problems.

Alternative thing to consider is activating the iCOD CPUS and add memory. Do you observe page-outs in vmstat? Maybe your system is swapping when the backupserver starts heavy processing, you can't get that under control with nice or anything else but more memory...

Regards,
Bernhard

[Michael Schulte zur Sur]

Hi,

please check, if the backup server using dump compression. You may use a compression, which is too high and have to explicitly assign a lower one. I found this at sybase.com

instead of
dump database to "compress::/work/compressed.dmp"
use
dump database to "compress::1::/work/

greetings,

Michael

[Raul Aviles]

Hi,
Michael : I have been checking information about backup server in sybase.com but i don´t find anything about the compress parameter. Would you please send me the article about the configuration of compress parameter

Thanks in advan

[Michael Schulte zur Sur]

Hi,

have a look at:
http://info.sybase.com/resolution/detail.stm?id_number=10840416
http://info.sybase.com/resolution/detail.stm?id_number=10878193
http://info.sybase.com/resolution/detail.stm?id_number=10416279
http://info.sybase.com/resolution/detail.stm?id_number=10947935

I hope, that one of these gives a clue to your problem,

Michael