Ken,
you're fairly optimistic about your sustained Ethernet transfer rates : if the
theoretical max throughput of your 100Mbps card is 100 Megabit per sec, in
practice it will not get much higher than (Ethernet, remember) 20-25% of that,
or 20-25 Megabit per sec.
We have just that situation: the media/master server is currently reached via a
100Mbps card, but the backup speeds are allways never more than 2.5 megabyte
per sec, or (2.5*8=) 20 Megabit per sec...
In other companies I got the budget to add a separate backup/restore LAN
segment, again with a 100 Mbps card. This isolated backup traffic from other
business-oriented traffic, so there I got typically in the range of 50-70% of
theoretical Ethernet speed, which was already much better than 20%.
Here I am trying to convince management to get combination of both: a separate
backup/restore LAN segment, composed of a single Ethernet switch, that bears 4
Gigabit Eth ports, that I will dedicate to the heaviest occupied server ports:
backup-media server, plus 2 database servers.
My experience from a previous job is that in this case, it's largely sufficient
(1000Mbps = 125 MBps theoretical = 60-78MBps practical) to drive up to 3 SDLT
or LTO tape drives at full speed.
Just take care of the next bottleneck which will appear then: the connection
host <-> tape robot : if on Ultra-SCSI, you're at approx 80 MBps. Some robots
have a Fibre-Channel port, giving you approx 110 MBps between host and robot.
Rgds
Rob
-----Original Message-----
From: veritas-bu-admin AT mailman.eng.auburn DOT edu [mailto:veritas-bu-admin
AT mailman.eng.auburn DOT edu] On Behalf Of SIBLEY, Ken R. - ACCOR-NA
Sent: Friday, June 11, 2004 5:46 PM
To: 'veritas-bu AT mailman.eng.auburn DOT edu'
Subject: RE: [Veritas-bu] FW: Multistreaming/Multiprexing
There is no set optimum setting for multistreaming or for multiplexing. It is
something you have to keep adjusting as you add/delete/upgrade servers.
The best thing I can tell you for immediate results is if possible put Gbit in
your media servers. Your current environment (assuming the master is also a
media server) is 3x100Mbit worth of traffic at a time no matter how many tape
drives you have/use. 300Mbit/8 =
~37.5MB/sec. Since the SDLT's are going to be at least 11 MB/sec uncompressed
(depeneding upon the model) you cannot drive all the drives full speed.
Putting Gbit into the media servers will change to 3000Mbit/8 = 375MB/sec.
There are a few additional things to cover such as speed of media servers,
memory, load on the system, speed of servers with largest concentration of
data, etc.
This is by no means a final answer, but should be a good starting point.
Good Luck,
Ken
--
Sr Unix Admin
Accor North America
ksibley AT accor-na DOT com
469-737-3370
-----Original Message-----
From: Ashraff Khan [mailto:AshraffK AT teletext.co DOT uk]
Sent: Friday, June 11, 2004 4:29 AM
To: 'veritas-bu AT mailman.eng.auburn DOT edu'
Subject: [Veritas-bu] FW: Multistreaming/Multiprexing
We are currently running Veritas NetBackup V3.4 for our centralised backup
solution and are experiencing problems with the every expanding backup windows
which is currently taking around 12hrs to backup 750GB of data. Our systems
spec: 2 x Qualstar TLD6460 sixty slots and 2 x SDLT drives in each library.
1 x Master and 2 x Media servers controlling each library.
We are currently backing up a total of 70 servers on the network which are all
connecting through 100MB full-duplex switched network. The total data being
backed up on a daily basis is around 750GB, but total data in library is around
10TB because it takes so long to duplicate the data. We are currently holding
data with retention period of 1 month.
Questions:
1. How can we reduce the backup windows considerably?
2. How can we reduce the retention period?
3. How can we speed up the tape duplication process?
4. How can we utilise multistreaming and multiplexing to reduce backup
window?
5. What is the optimum setting for multistreaming and multiplexing in
our environment?
6. What is the total throughput of the SDLT drives i.e. MB per sec.
7. How can we utilise the two drives in the library to double the
throughput.
Thanks
Ash.
Ashraff Khan
Principal Systems Project Manager
IT Systems
Teletext Ltd.
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