Hi
Been working with Netbackup for a couple of years and you
sort of get set in the way that you do things.
There are curtain parameters that you always set the same,
like “Maximum jobs per client” = 99.
“Allow media overwrite” = I tick all of them …
So I wondered what and why you set some of the following
settings:
1.
Storage Units:
You have 2 x LTO4 drives. Would you create one stu
with two drives in it or would you create a stu for each drives?
# I’ve found that in some cases it better to create
two stu’s. When a policy starts, it “grabs” the allocated stu and although it
only uses the one drive, it holds on to the other and the next backup queue’s.
With two separate stu’s, the one drive is always available when one is in use.
To make use of the other drive if the policy should need it, the stu is not made
“On demand only” and Storage Unit in the policy is set to “Any Available”. Also
if one drive goes down, the storage unit can still allocate the working
drive.
@ Your thoughts?
Answer: Alot depends on the environemnt, but it may be
incorrect to do this. And also if the same tape that is being used for
backups is going to the same volume pool. One environment I know has 6 drives and has a
storage unit for all 6 LTO4 drives, but for Month End Backup, a seperate storage
unit is created for just 4 drives. Normally, maximim multiplexing is running, to
allow as many jobs as possible to be written to the same tape. Again, alot would
depend on the environment, and what you are looking for. If you are not running
a 24 x 7 environment, you may find that you have free drives available for
additional backups or restores.
2.
Multiplexing:
Maximum streams per drive:
# The rule of thumb is – The drive should never wait
for the host to send or receive data. That said, what would you suggest the
“Maximum streams per drive” should be and why for:
LTO2
LTO3
LTO4
# In my case I usually go for LTO2 = 3 to 5 streams,
LTO3 = 5 to 6 streams and LTO4 = 5 to 8. This depends on the server / OS /
network and a few other factors such as NUMBER_DATA_BUFFERS and
SIZE_DATA_BUFFERS, so it becomes an art to get it just right.
@ Your thoughts?
Answer: Again, one environment has
the STU as Multiplexed as 32, but in some cases, has policies and seperate
storage unit that is set to Multiplex 6 streams to a drive. This is mainly
for larger type file systems. One policy has over 50 clients, using the
ALD, and its important to get as many streamed across all drives as possible to
get the faster backups. To date, we have not really seen any real impact on
restores. Some SAN Media Servers have been tuned with data_buffers and
size_data_buffers (ie: Oracle, SQL, Exchange) to get the most data flowing
through the drives. Just be sure it does not impact restores
:)
3.
VSP:
Netbackup creates a VSP directory and creates a *.vsp
file in this directory. In some cases it does not remove this *.vsp file after
the backup completes and eventually it fills up all the space on the server’s
drive. When you try and delete the file, you cannot as it gives “in use” error.
Only way is to reboot the server and delete vsp file just after the server comes
up again. (There is a tech note on how to delete without reboot, but few clients
opt for this option).
# We disable VSP for all clients. This might not be
the best option, but it causes the backup to start off without delay and
prevents the vsp file to be created. We then only allow VSP to be active on
servers that needs to backup open files.
@ How do you guys handle this one?
Answer: Use VSS for Windows based backups for 2003
onwards - I try to avoid VSP myself. There is a tool that can remove
the "lock" that allows you to delete the file. Check http://seer.entsupport.symantec.com/docs/270127.htm for
more details. The subject is
also covered in the Admin Guide as well, to try to find tune VSP, however as we
are going to Win2k3 / 2k8, VSP will not play a part here.... but again, it may
differ in environments.
REMEMBER: JUST my own views !
Some others you guys can think off?
