Couple of questions re buffers...

[sdo]

Hi Peeps, I have an N5220 (v2.0.3 - v7.1.0.8) that shows this is bptm log: ... 00:03:58.613 [3965] <2> read_config_file: using 524288 value from /usr/openv/netbackup/db/config/SIZE_DATA_BUFFERS_DISK 00:03:58.613 [3965] <2> io_init: using 524288 data buffer size 00:03:58.613 [3965] <2> set_job_details: Tfile (1691875): LOG 1392077038 4 bptm 3965 using 524288 data buffer size ... 00:03:58.613 [3965] <2> io_set_recvbuf: receive network buffer is 262144 bytes 00:03:58.625 [3965] <2> read_config_file: using 64 value from /usr/openv/netbackup/db/config/NUMBER_DATA_BUFFERS_DISK 00:03:58.625 [3965] <2> io_init: using 64 data buffers 00:03:58.625 [3965] <2> set_job_details: Tfile (1691875): LOG 1392077038 4 bptm 3965 using 64 data buffers 00:03:58.625 [3965] <2> io_init: child delay = 10, parent delay = 15 (milliseconds) ... This N5220 has the following buffer files: /usr/openv/netbackup/NET_BUFFER_SZ - file does not exist /usr/openv/netbackup/db/config/NUMBER_DATA_BUFFERS - file does not exist /usr/openv/netbackup/db/config/NUMBER_DATA_BUFFERS_DISK - file exists, and contains 64 /usr/openv/netbackup/db/config/SIZE_DATA_BUFFERS - file does not exist /usr/openv/netbackup/db/config/SIZE_DATA_BUFFERS_DISK - file exists, and contains 524288 Questions: 1) Is it normal for bptm to use the _DISK value files if it doesn't find the tape value files ? 2) Will tape media written with the 512KB buffer size (above) actually be readable on a RedHat 5.9/10 media server that has a SIZE_DATA_BUFFERS of 256 KB ? 3) Are tapes written by a 7.1.0.8 (i.e. 2.0.3) N5220 appliance readable on a v7.0.1 media server ? Thanks, Dave.

[Nicolai]

1: Netbackup uses default values is none is specified. NUMBER_DATA_BUFFERS/SIZE_DATA_BUFFERS are used for tape backups the _DISK are used ... well for disk based backups .

2:Yes - Netbackup uses a variable block size detection mechanism.

3: Syamantec has not changed the tape format i years - so if you follow the formal import/export procedure you should be good. Please note there may be Netbackup specific dependencies - you need to read this t/N

http://www.symantec.com/business/support/index?page=content&id=TECH29677 

[Marianne]

3) Are tapes written by a 7.1.0.8 (i.e. 2.0.3) N5220 appliance readable on a v7.0.1 media server ?

If new features were used in the 7.1 backup, the 7.0 media server will probably not be able to read the tape.

Why not upgrade the 7.0 media server? 7.0.1 was released on 2010-08-24 with NO subsequent updates/fixes,etc...

[sdo]

Found I was looking at the bptm child job of a bpdm parent - from an SLP activity - hence bptm picking up the _DISK file settings.

Re variable block size mechanism...

I have tested that a Windows 2008 R2 x64 media server running NetBackup v7.5.0.7 with SIZE_DATA_BUFFERS of 256 KB:

- is able to read/write LTO5 (via SAS interface) media with 256 KB buffers

- and read DAT DDS-4 4mm (via SCSI) media previously written with 64 KB buffers

- but is unable to write to the old DAT DDS-4 4mm because the device maximum buffer size is 64 KB.

So, NetBackup can tolerate reading older tapes written with smaller buffers...

...but doesn't appear to have a mechanism of specifying which buffer size to use for writing to any given tape drive...

...having said that, I haven't yet tested removing the SIZE_DATA_BUFFERS file, to see if NetBackup is able to auto detect maximum buffer size and adjust itself accordingly for writes on a per tape drive basis.

And, I think this is how to check which version of GNU tar is embedded within NetBackup tar:

From a RHEL 5.9 server running NetBackup v7.0:

# /usr/openv/netbackup/bin/goodies/support/versioninfo -s -f /usr/openv/netbackup/bin/tar | egrep -i "netbackup|create"

======= /usr/openv/netbackup/bin/tar =======

@(#) NetBackup_7.0 3438014654

@(#) $Source: src/cl/tar/create.c,v $ $Revision: 1.19 $

From a RHEL 5.9 server running NetBackup v7.0.1:

# /usr/openv/netbackup/bin/goodies/support/versioninfo -s -f /usr/openv/netbackup/bin/tar | egrep -i "netbackup|create"

======= /usr/openv/netbackup/bin/tar =======

@(#) NetBackup_7.0.1 1978966145

@(#) $Source: src/cl/tar/create.c,v $ $Revision: 1.19 $

From a RHEL 5.9 server running NetBackup v7.1.0.4:

# /usr/openv/netbackup/bin/goodies/support/versioninfo -s -f /usr/openv/netbackup/bin/tar | egrep -i "netbackup|create"

======= /usr/openv/netbackup/bin/tar =======

@(#) NetBackup_7.1.0.4 71367259

@(#) $Source: src/cl/tar/create.c,v $ $Revision: 1.21 $

From an N5220 running Appliance v2.0.3:

# /usr/openv/netbackup/bin/goodies/support/versioninfo -s -f /usr/openv/netbackup/bin/tar | egrep -i "netbackup|create"

======= /usr/openv/netbackup/bin/tar =======

(#) NetBackup_7.1.0.8 3281035395

@(#) $Source: src/cl/tar/create.c,v $ $Revision: 1.21.48.1 $

The GNU tar manual:

https://www.gnu.org/software/tar/manual/tar.pdf

Page with GNU tar revision history:

http://www.gnu.org/software/tar/