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Mike,
Last January, I implemented a VTL (EMC CDL720) with 35
usable TB. We did much study on the multiplex issue in most instances the
backup did perform faster when it was not multiplexed, but with out a doubt the
restore AND duplications speed is around 4 times as fast. So, I am working
towards having enough tape drives to stop all multiplexing in my
environment.
Here are my 2 issues....
I have a heavily clustered environment with 27 Media
Servers. Well, an ORACLE DB could fail over from one server at any
time. Well, when I originally setup the servers with 1 or 2 drives each,
there was not enough on a robot with 20 drives to have the same robot on each
media server. Well, what happens when the server A goes down that points
to robot 1, and the DB fails over to server B and it only sees robot 2?!?
I would have to scramble to make robot 1 visible on server B. I did see
something in the VTL that might allow me to transfer the tape over from one
robot to another and then I guess I would inventory the robot.... but alas I am
unsure.
Issue 2.... I do all my vaulting on my master server.
Since my media servers are also production servers, I do not want to hit them
with so much IO for duplication. So the master server needed to have tape
drives on each robot.
So, I after much thought and upgrading to 6.5 I realized
that SSO is not so bad. In fact it is wonderful! Media servers and
join the SSO and pull out of it with no need to shutdown netbackup on the master
server! Configuring tape drives is one step away by typing "tpautoconf
-a".
Also, now I share the robots with in the VCS clusters and
make sure that each server in the cluster can see all the robots. So, I
can do restores with out any issues.
Lastly, I don't have to generate 13 robots with 20 tape
drives each to turn off multiplexing! Yes, that is how many tape drives I
would have needed to meet that demand.
So, I recommend that you don't turn away from SSO. I
believe it is still a great feature and runs so much smoother in
6.5.
P.S..... Actually I would say NOT to purchase a VTL.
I believe with all the new great features in NB 6.5, make the Disk Staging Units
to be the best options for most people.
P.S.S.... Remember when you turn off multiplexing on the
VTL, you will HAVE TO over subscribe the number of tapes, so that you don't run
out of media!
Please feel free to e-mail me any other
questions.
Kevin
Hi,
I am currently testing my NetBackup environment to backup to VTL.
We are seeing great backup performance but it seems like it requires a slight
re-architecture to the current environment. I am being told to eliminate
multiplexing... You can multiplex to a virtual drive but when it comes time to
restore and to duplicate off to physical tape from a virtual cartridge that was
multiplexed the performance is not very good. The Vendor said that multiplexing
should be eliminated and instead of increasing multiplexing you can simply
create additional virtual drives when needed. Since adding virtual tape drives
in theory has no cost associated with it why not do this and eliminate
multiplexing and SSO all together (that is the approach/mentality).
So my
question to the forum is have others deployed VTLs in a similar fashion (i.e.
MPX = 0) and how have things scaled and is there any associated management
headaches? The couple con's of the above approach in my mind would be:
*
Slower responding NBU GUI because there will be so many devices it will have to
manage/query
* More BPTM processes since each tape drive in use requires one
an additional BPTM process
* Slower backups on a per stream basis (which is
OK because you have many drives I guess)
Can anyone comment if they
foresee other drawbacks to this approach or have best practice recommendations?
Thank in advance for any
feedback...
-Bill
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