Veritas-bu

[RE: [Veritas-bu] OTM problems on W2K]

2002-03-18 10:04:37
Subject: [RE: [Veritas-bu] OTM problems on W2K]
From: javier.graf AT usa DOT net (jago)
Date: Mon, 18 Mar 2002 07:04:37 -0800
Hi John,

Please take a break an read the following;

Sincerely

T4B Group AG

 

Javier González

GM IT Services

 

Regensdorferstrasse 15

CH-8049 Zürich

Tel:          +41 1 342 58 90

Fax:         +41 1 342 58 91

Mobile:     +41 76 384 2002

jg AT t4b DOT ch

www.t4b.ch


-----------------------------------------------------------

On Windows NT/2000 systems, verify that there is enough room in the disk
partition where NetBackup is installed.

Verify that the system is not running out of virtual memory. If virtual
memory is the problem, shut down unused applications or increase the amount
of virtual memory.
To increase virtual memory on Windows NT/2000:
a. Display the Control Panel.
b. Double-click System.
c. On the Performance tab, set Virtual Memory to a higher value.

 Examine other activity logs or the status on the client.

You might also need to examine the services file:
verify that the %SystemRoot%system32driversetcservices file has the correct
entries for bpcd, bpdbm, and bprd.
Also, verify that the NetBackup Client Service Port number and NetBackup
Request Service Port number on the Network tab in the NetBackup
Configuration dialog match the settings in the services file. To display
this dialog, start the Backup, Archive, and Restore interface and click
Configure on the Actions menu. The values on the Network tab are written to
the services file when the NetBackup Client service starts.


Disk Cache settings are an integral component for OTM operations. The
documented defaults for the cache settings are "initial = 10MB" and "max =
50MB". However, best results have been achieved with the OTM cache settings
as "initial=100MB" and "max=0MB".  Because of the diversity of environments,
these settings will vary.  Manually configured values may be needed due to
low free disk space or the amount of data to be backed up. Below are some
recommendations to allow OTM to work as dynamically as possible. Sufficient
disk space is required for OTM to be operational. Insufficient system
resources may prevent implementation of OTM in the operating environment.
Also, OTM may not be a viable open file manager solution on NT servers that
are extremely busy. OTM needs a "quiescent" or inactive period of time (5
seconds by default) to create a snapshot of a disk partition.  Backup jobs
that run when the level of disk activity is high, or a "quiescent", or
inactive period of time cannot be achieved, will end with an "exit status
code:  1".  This indicates the backup was only partially successful.


Recommendations:

These settings will allow the most scalability with OTM.  These settings are
not guaranteed to work on all NT servers. Depending on free disk space or
available memory, these settings may have to be manually configured. 

1.  SNAPSHOT TYPE: Set OTM snap shot type to "Individual" unless multiple
data streams is enabled.  The "Individual" setting will allow OTM to create
a snapshot per drive and will allow the cache file to be minimum size as a
snapshot of one drive at a time will occur.  This setting is recommended for
servers with low disk space and when Multiple Data Stream backups are not
enabled.  

2.  INITIAL CACHE SIZE: Set Initial cache size to 100MB.  OTM will create
the initial cache file before the backup starts. An initial cache setting of
100MB will allow the backup to start faster, but may slow performance
slighty if the cache file needs to grow during the course of the backup due
to open file activity.  Setting this value higher will create a longer delay
at the start of the backup until the cache file has been created.  Creating
a larger Initial cache file may increase performance during backups if
frequent disk writes occur during the backup.  The time for building the
initial cache file will primarily depend on CPU speed and server activity.

3.  MAX CACHE SIZE: Set Max cache size to 0MB.  With the Max Cache Size set
to 0MB, OTM will calculate 10 percent of the used disk space as its maximum.

- When "Global" is set for the snap shot type, OTM will calculate 10 percent
of all used disk space for all disks included in the file list to be backed
up.                                         
 - When "All Available" is set for the snap shot type, OTM will calculate 10
percent of all used disk space for all local disks on the server including
drives that are not specified in the file list of files to be backed up.
This value may need to be manually configured on some NT server that have
over 35GB to be backed up (See below in        Caveats).

4.  CACHE FILE FIELD: Ensure the "Cache file" field is not configured or
left blank. The Cache file field is used to allow the user to define the
location of the Cache File. If this field is blank, OTM will dynamically and
automatically place the cache file on a drive that has the most free space.
OTM will attempt to place the cache file on a drive that is not being backed
up. Due to available disk space, the cache file may end up on the drive that
is active during the backup. When this occurs, the Initial cache file
setting is not used and OTM will create an Initial cache file the same size
as the maximum cache file size.

5.  OTM ERROR CONTROL: Set "OTM Error Control" to "Retry OTM".  This will
allow NetBackup to pause the backup when the cache file fills up. OTM will
then destroy the cache file, create another snapshot of the drive(s), and
continue the backup.

6. CACHED FILES: It is recommended the minimal value for this field is set
to 100. When this field is set to 0, the cache file will not grow beyond the
size of the configured "initial cache file" size. This applies even if a
maximum cache file size set. Setting this field to 100 allows the cache file
to flush the changed files after every 100 open files have been backed up.
Additionally, a setting in the cached file field allows the cache file to
expand beyond the initial cache file setting.  If the system contains a
large number of small files (file size less than 100K), it is recommended to
increase this setting.    

CAVEATS

OTM cannot be used over a mapped drive or on a shared drive of a cluster if
the node does not have control of the drive.  Blue Screens are a common
symptom of mapping drives on nodes that do not have control of the drive.  

Multiple Data Streams 
Multiple Data Streams is set for improvements in performance. However, this
setting also requires additional system resources to be available when
configured. 

If the class configuration in NetBackup is set for multiple data streams, it
is necessary to set the following parameters for this feature to operate:
- Snapshot type must be set to "Use all available drives".
- On the Master server, within the NetBackup Global Attributes, the "maximum
jobs per client" must be equal to, or more than the number of streams being
used.

Please refer to the following link for Microsoft limitations while utilizing
NetBackup's OTM feature:

http://support.microsoft.com/support/kb/articles/Q126/4/02.asp?LN=EN-US&SD=g
n&FR=0&qry=Q126402&rnk=3&src=DHCS_MSPSS_gn_SRCH&SPR=MSALL

WIN2K Specific Caveats:

File Systems < 30GB


- Max Cache size can be set to 0MB, this setting will allow autocache
configuration of 3000 MB (3GB or 10% of 30GB).


File System > 30GB

- The error control setting must be set to "Retry OTM".
- Max cache size must be manually configured to 3000MB or less.
- This setting will avoid the MS limitation listed above.



OTM uses a "Kernel" mode driver.  The most memory kernel mode drivers in
WIN2K can allocate is roughly 380MB of memory and is shared by all kernel
mode drivers in the system.  OTM uses 40KB of available memory per MB of OTM
cache file.  Depending on the number of kernel mode drivers on the server,
the maximum cache file size on any WIN2K server is approximately 3GB.  On
servers with > 30GB of data, it may be necessary to manually configure the
Maximum Cache file size downward. This is dependent on the memory being
utilized by other kernel mode drivers on the server.  To specifically
validate if OTM has reached the available kernel driver memory limitation or
have reached a physical memory limitation,  look for the following in the
bpbkar log "OTM: not enabled (err = 0x000005aa)" from the client.  This
indicates the kernel mode driver memory or available physical memory has
reached its limit. The backup will continue but will not utilize OTM and the
backup job will end with an exit code of "Status 1" - not all files backed
up. A smaller Maximum cache file size will be needed if it has been
determined that there is enough available physical RAM in the server.




NT 4.0 Specific Caveats:

File System < 20GB

- Max Cache size can be set to 0MB. 
- This setting will allow autocache configuration of 2000 MB (2GB or 10%).
- This setting will avoid the MS limitation listed above.


File System > 20GB

- The error control setting must be set to "Retry OTM".
- Max cache size must be manually configured to 2000MB or less.
- This setting will avoid the MS limitation listed above.



OTM uses a "Kernel" mode driver.  The most memory kernel mode drivers in NT
4.0 systems can allocate is roughly 192MB of memory and is shared by all
kernel mode drivers in the system.  OTM uses 40KB of available memory per MB
of OTM cache file.  Depending on the number of kernel mode drivers on the
server, the maximum cache file size on any NT 4.0 Servers is approximately
2GB.  On servers with > 20GB of data, it may be necessary to manually
configure the Maximum Cache file size downward. This is dependent on the
memory being utilized by other kernel mode drivers on the server.  To
specifically validate if OTM has reached the available kernel driver memory
limitation or have reached a physical memory limitation,  look for the
following in the bpbkar log "OTM: not enabled (err = 0x000005aa)" from the
client.  This indicates the kernel mode driver memory or available physical
memory has reached its limit. The backup will continue but will not utilize
OTM and the backup job will end with an exit code of "Status 1" - not all
files backed up. A smaller Maximum cache file size will be needed if it has
been determined that there is enough available physical RAM in the server.


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