Re: [Veritas-bu] Real World NBU Buffer settings Win2k3
2010-09-16 09:09:08
Hi William
Well it wont accept the settings, so I am going to look
at:
1) Flash Backups
2) Try backup to disk
3) Use NTBackup
have a comparison to work with. I also have an Eval License of
all features! Hooray!
Quesiton: Can anyone confirm the best way to setup Flash
Backups. Running through the Beginners Guide now (Quick Start Guide), but need
to know of any "gotchas"! - Just learned it cannot do system
volumes.
S.
We
use 262144 buffer size everywhere for both NET_BUFFER_SZ and tape
SIZE_DATA_BUFFERS (or Windows equivalent). What I did find made a very
large difference when I was benchmarking an LTO4 drive (which has a 4Gb FC
interface) was switching between a 2Gb HBA and a 4Gb HBA – the throughput nearly
doubled. That was testing with ‘dd’ not NetBackup, but was going through
the (Solaris) OS. So I would see if there is any way that you can up the
speed, even if you go point-to-point and not via a SAN switch to avoid having to
upgrade your fabric [no use if you share the drives with
SSO!]
For
Windows on FC you should find any modern FC driver will use the tape buffer size
that you set. 64k was with the Windows scsi driver, and for some SCSI
cards you might have to adjust the MaximumSGList in the registry – (http://mailman.eng.auburn.edu/pipermail/veritas-bu/2006-February/083653.html)
and (http://h20195.www2.hp.com/v2/GetPDF.aspx/5982-9971EN.pdf). More
recent Adaptec driver install kits I have noticed do this for you. You
should be able to see in the bptm log what size is being used. The fact
you say the tape would not mount if you change settings *is*
suspicious. Make sure you have the latest drive/robot settings files so
your drives are properly set to variable block size. Again bptm log should
help.
If
the data is compressed on disk then I assume the Windows OS is having to
decompress on the fly as it reads the disk which is going to hit the client
quite hard on the CPU. Not much you can do about that, but FlashBackup
would not have to do that so I’d say was worth trying. Bear in mind it
will back up the entire volume, so you don’t want to be backing up a lot of
empty space (though paradoxically that empty space would compress nicely when it
hits the LTO drive’s h/w compression, provided Windows is zeroing the blocks on
file deletion…not sure if it does this or even can be made to…otherwise you have
a great disk scavenger ;-) ).
William
From:
veritas-bu-bounces AT mailman.eng.auburn DOT edu
[mailto:veritas-bu-bounces AT mailman.eng.auburn DOT edu] On Behalf Of WEAVER,
Simon (external) Sent: 15 September 2010 19:00 To:
veritas-bu AT mailman.eng.auburn DOT edu Subject: [Veritas-bu] Real World NBU
Buffer settings Win2k3
Hi
All Anyone
got any real world experience on buffer settings:
scenarion:
Win2k3
San Media, connected to 2GB Fabric attached 8 LTO4 Drives. Due to
drive availability, Multiplexing onto one drive.
Main
problem: One volume (1,7tb in size) takes over 4 days to fully complete.
Got the
Tuning Guide and Technote 244602, but I tried some settings, only to find the
backup would not even mount tape correctly.
So back
to "no" settings at the mo.
Volume
are generic files/folders, mixture of large and small sizes. But 1.7TB's in my
view should be done quicker. Also Data is compressed.
Regards
Simon
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