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Netbackup performence slow on backup to disk

June
Not applicable
I have two luns from netapp filer on my netbackup master server and make a diskpool. the backing up to diskpool is slower then backing up to tape. I tested on the same client. What can Ido to increase the speed.?

thanks
1 REPLY 1

Rakesh_Khandelw
Level 6
There are lots of things you can look at such as.. how the lun was created, single disk vs multiple disks, what kind of disks are these FC Vs SATA, how the storage is connected to host Fiber Vs SCSI/iSCSI, what kind of bus at what speed at host is connected to storage etc...

You may not have control on all of the above mentioned but you can try adjusting buffer settings on your server. I suggest you download Backup Planning and Performance Tuning guide and go through it. Below are excerpts from the guide -

For unix - /usr/openv/netbackup/db/config/NUMBER_DATA_BUFFERS_DISK
For Windows - <install_path>\NetBackup\db\config\NUMBER_DATA_BUFFERS_DISK

These files contain a single integer specifying the number of shared data buffers
NetBackup will use. The integer represents the number of data buffers. For
backups (in the NUMBER_DATA_BUFFERS and
NUMBER_DATA_BUFFERS_DISK files), the integer’s value must be a power of
2.
If the NUMBER_DATA_BUFFERS file exists, its contents will be used to
determine the number of shared data buffers to be used for multiplexed and
non-multiplexed backups.
NUMBER_DATA_BUFFERS_DISK allows for a different value when doing
backup to disk instead of tape. If NUMBER_DATA_BUFFERS exists but
NUMBER_DATA_BUFFERS_DISK does not, NUMBER_DATA_BUFFERS applies
to all backups. If both files exist, NUMBER_DATA_BUFFERS applies to tape
backups and NUMBER_DATA_BUFFERS_DISK applies to disk backups. If only
NUMBER_DATA_BUFFERS_DISK is present, it applies to disk backups only.
If the NUMBER_DATA_BUFFERS_RESTORE file exists, its contents will be used
to determine the number of shared data buffers to be used for multiplexed
restores from tape.

The NetBackup daemons do not have to be restarted for the new values to be
used. Each time a new job starts, bptm checks the configuration file and adjusts
its behavior.

Changing the size of shared data buffers

Caution: It is critical to perform both backup and restore testing if the shared
data buffer size is changed. If all NetBackup media servers are not running in
the same operating system environment, it is critical to test restores on each of
the NetBackup media servers that may be involved in a restore operation. For
example, if a UNIX NetBackup media server is used to write a backup to tape
with a shared data buffer (block size) of 256 Kilobytes, then it is possible that a
Windows NetBackup media server will not be able to read that tape. In general, it
is strongly recommended you test restore as well as backup operations, to avoid
the potential for data loss.

To change the size of the shared data buffers, create the following file on the
media server:

UNIX
For tape
/usr/openv/netbackup/db/config/SIZE_DATA_BUFFERS
For disk
/usr/openv/netbackup/db/config/SIZE_DATA_BUFFERS_DISK

Windows
For tape
install_path\NetBackup\db\config\SIZE_DATA_BUFFERS
For disk
install_path\NetBackup\db\config\SIZE_DATA_BUFFERS_DISK


This file contains a single integer specifying the size of each shared data buffer
in bytes. The integer must be a multiple of 32 kilobytes (a multiple of 1024 is
recommended); The integer represents the size of one tape or disk buffer in bytes. For example, to use a shared data buffer size of 64 Kilobytes, the file would contain the integer 65536.

The NetBackup daemons do not have to be restarted for the parameter values to
be used. Each time a new job starts, bptm checks the configuration file and
adjusts its behavior.

IMPORTANT: Because the data buffer size equals the tape I/O size, the value
specified in SIZE_DATA_BUFFERS must not exceed the maximum tape I/O size
supported by the tape drive or operating system. This is usually 256 or 128
Kilobytes. Check your operating system and hardware documentation for the
maximum values. Take into consideration the total system resources and the
entire network. The Maximum Transmission Unit (MTU) for the LAN network
may also have to be changed. NetBackup expects the value for NET_BUFFER_SZ
and SIZE_DATA_BUFFERS to be in bytes, so in order to use 32k, use 32768 (32 x
1024).

Note: Some Windows tape devices are not able to write with block sizes higher
than 65536 (64 Kilobytes). Backups created on a UNIX media server with
SIZE_DATA_BUFFERS set to more than 65536 cannot be read by some Windows
media servers. This means that the Windows media server would not be able to
import or restore any images from media that were written with
SIZE_DATA_BUFFERS greater than 65536.

Note: The size of the shared data buffers used for a restore operation is
determined by the size of the shared data buffers in use at the time the backup
was written. This file is not used by restores.

Recommended shared memory settings

The SIZE_DATA_BUFFERS setting is typically increased to 256 KB and
NUMBER_DATA_BUFFERS to 16. To configure NetBackup to use 16 x 256 KB
data buffers, specify 262144 (256 x 1024) in SIZE_DATA_BUFFERS and 16 in
NUMBER_DATA_BUFFERS.
Note that increasing the size and number of the data buffers will use up more
shared memory, which is a limited system resource. The total amount of shared
memory used for each tape drive is:
(buffer_size * num_buffers) * drives * MPX
where MPX is the multiplexing factor. For two tape drives, each with an MPX of
4 and with 16 buffers of 256k, the total shared memory usage would be:
(16 * 262144) * 2 * 4 = 32768 K (32 MB)
If large amounts of memory are to be allocated, the kernel may require
additional tuning to allow enough shared memory to be available for
NetBackup's requirements.

Note: Note that AIX media servers do not need to tune shared memory because
AIX uses dynamic memory allocation.
Be cautious if you change these parameters. Make your changes carefully,
monitoring for performance changes with each modification. For example,
increasing the tape buffer size can cause some backups to run slower. Also,
there have been cases with restore issues. After any changes, be sure to include
restores as part of your validation testing.
Testing changes made to shared memory
After making changes, it is vitally important to verify that the following tests
complete successfully:
1 Run a backup.
2 Restore the data from the backup.
3 Restore data from a backup created prior to the changes to
SIZE_DATA_BUFFERS and NUMBER_DATA_BUFFERS.
Before and after altering the size or number of data buffers, examine the
buffer usage information in the bptm debug log file. The values in the log
should match your buffer settings. The relevant bptm log entries are similar
to the following:
12:02:55 [28551] <2> io_init: using 65536 data buffer size
12:02:55 [28551] <2> io_init: CINDEX 0, sched bytes for
monitoring = 200
12:02:55 [28551] <2> io_init: using 8 data buffers
or
15:26:01 [21544] <2> mpx_setup_restore_shm: using 12 data
buffers, buffer size is 65536
When you change these settings, take into consideration the total system
resources and the entire network. The Maximum Transmission Unit (MTU)
for the local area network (LAN) may also have to be changed.