Hi, Guys,

I have system performance problem when backuping DB to tapes (IBM 3583)
using NBU4.5 and RMAN.

My system: 2 CPU/2 GB RAM with 4 GB swap;
OS: AIX5.1 (32bit) Application: Oracle8174(32bit)
The hot device is hdisk3, a RAID 0+1. I used only 1 channel to backup DB
in RMAN, and the Netbackup buffer is 8 with 32K bytes.)

Firstly I got hign PageIn/PageOut in vmstat 10 results.
After the setting of MINPERM & MAXPERM was changed (from -p 20 -P80 to
-p 5 -P 20), the page in &out is nearly zero now.
I also used the vmtune -R 64 to increase page ahead read. Other
parameters of vmtune are default.
But the CPU wait is still very high, almost kept above 80% when reading
DB files. Is there any clue to solve the problem?
#lsps -s
Total Paging Space Percent Used
4096MB 3%
#vmstat 10
kthr memory page faults cpu
----- ----------- ------------------------ ------------ -----------
r b avm fre re pi po fr sr cy in sy cs us sy id wa
1 3 404782 38964 0 0 0 1736 8660 0 1671 1142 3612 2 8 5 85
1 3 405393 38355 0 0 0 1729 23493 0 1738 2086 3757 3 9 4 84
1 3 404782 38969 0 0 0 1763 23612 0 1877 7998 4033 2 9 6 83
3 405396 38353 0 0 0 1739 5556 0 1712 1160 3696 2 8 5 84
1 3 404785 38963 0 0 0 1656 16720 0 1772 1802 3859 2 9 4 85
3 3 405400 38346 0 0 0 1755 3692 0 1726 1526 3725 2 10 6 83
2 3 404786 38958 0 0 0 1681 4702 0 1721 1114 3713 2 8 6 83
3 405399 38349 0 0 0 1694 21699 0 1768 2025 3807 2 9 4 85
1 3 404786 38964 0 0 0 1707 4707 0 1722 1117 3719 2 9 5 84
2 3 405861 37884 0 0 0 1525 41280 0 1487 1349 3213 3 8 8 81
1 403484 41230 0 0 0 18 60 0 330 3614 654 1 3 87 9
1 1 405341 38406 0 0 1 23 81 0 448 4305 808 3 4 80 13
1 2 404723 39026 0 0 0 23 82 0 353 3009 749 2 2 88 8
1 0 405336 38415 0 0 0 3 11 0 291 1464 517 1 1 95 2
1 405146 38601 0 0 0 15 45 0 291 2856 522 1 2 95 1
1 4 404751 38999 0 0 0 78 251 0 358 1694 669 1 2 92 4

Thanks in advance!
Laura

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Posted via http://dbforums.com

In article <3137470.1058867609@dbforums.com>, Mark Taylor <member20596@dbforums.com> wrote:
>
> get a faster tape solution

LTO's pretty quick, but LTO-1 requires you to use an intermediate disk pool
("disk staging area") of some sort because it's got terrible start/stop
performance characteristics.

Without a disk pool, we see about 1 MB/sec writes to LTO-1 tape, and with a
disk pool, about 22.5 MB/sec. LTO-2 (2nd gen LTO) is even better and also
has much better start/stop performance but still ideally, one wants to
stream from disk to tape at full speed with either generation of LTO tape
drives.

So...

clients->backup server[disk]->backup server[tape]

is still the best approach.

LTO start/stop performance is mentioned in an IBM white paper on LTO at:

ftp://ftp.software.ibm.com/software/...wp-tsm-lto.pdf

-Dan

Thanks a lot.

We do use LTO (3583) and disk pool.
And, I checked the backup log and found that the backup to tape transfer
rate was less than 1M/s.
But I don't know what are the correct number for NBU:
NUMBER_DATA_BUFFERS & SIZE_DATA_BUFFERS.

Any advice on them?

--
Posted via http://dbforums.com

Thanks guys.

I found the default value for Veritas Netbackup 4.5 is 8 buffers with
size 32K. I tried to use more buffers with larger size, but I don't know
the suitable value.

The sizes of some files are 5GB and above. So they cann't be small. I
tried to tune the Netbackup buffer to 32 buffers with 132K, but I have
to wait for the result.

Anyone have some advice on IBM3583 and Veritas Netbackup 4.5 for AIX?

--
Posted via http://dbforums.com