This is a horses for courses problem.
TSM across the network may not be the best solution for this server.
Instead use some tool which can write to directly attached tape drives.
If you want to use TSM install a TSM server on this box and use shared memory
or named pipes to provide efficient intenal comms. Run periodic selectives to
reduce the number of mounts.
Maybe you can use both solutions, ie a periodic (once a week?) full backup to
local tape and TSM daily incrementals. Restore procedure is then restore local
tape and bring up to date with TSM incrementals.
TSM is a swiss army knife. It is good for many situations but it is not
optimal for all.
Steve Harris
AIX and TSM Admin
Queensland Health, Brisbane Australia
>>> Daniel Sparrman <daniel.sparrman AT EXIST DOT SE> 19/12/2001 6:50:44 >>>
Hi
One of our customers is running a medium site with 180 servers, with about 10TB
of storage.
Their using an IBM 3584 Anaconda with 2 fibre attached drives.
The machine is a IBM P-Series 640, with RAID 1+0.
One of the largest servers is about 700GB. Its the fileserver running user data
and home directories.
Mount time, including search of files on the tape is about 2 min. When
restoring 1GB, the total time is about 8 min. This means That a total restore
of the server would take about 70 hours to complete. This formula is 2 mins to
search and mount tape, 6 mins to restore data.
The customers P-Series machine is equipped with 2 100Mbs Ethernet cards, and 1
IBM Token-Ring 100Mbs card. The test was on one of the ethernet cards.
Today, the customer is using OTG DiskXtender. This is for two reasons; one to
save primary diskspace, the other to minimize the amount of data that has to be
restored in an event of disaster.
The LTO drives can perform 15MB/s, or 30MB/s compressed.
The P-Series machine is not the bottleneck. Usually, the network sends about
3000 packets with a peak at 7000. During backup, 27.000 packets is sent with a
peak at 50.000. According to the communications guys, this is very high.
The clients is Compaq Proliant machines with about 4GB of memory, two
processors running at Xeon 750(i think).
So, there shouldn't be a bottleneck.
According to the communications guys, the maximum theoretical speed of 100Mbs
ethernet is about 12.5MB/s, or running at full duplex, 25MB/s. The first
problem with this is that this is a one way communication(server to client).
With 12.5MB/s restore time, the total restore of 700GB would take 15 hours.
Who has a primary fileserver that can be down for 15 hours?
And, this is only theoretical.
With 1GB ethernet, the theoretical capacity is about 30MB/s. And this is only
theoretical. The restore would take about 7.5 hours. Whats if this happend in
the morning? Would the users take vacation and come back the next day?
Just some thoughts....
Best Regards
Daniel Sparrman
-----------------------------------
Daniel Sparrman
Daniel Sparrman
Exist i Stockholm AB
Bergkllavgen 31D
192 79 SOLLENTUNA
xel: 08 - 754 98 00
Mobil: 070 - 399 27 51
Alex Paschal <AlexPaschal AT FREIGHTLINER DOT COM>
Sent by: ADSM: Dist Stor Manager<ADSM-L AT VM.MARIST DOT EDU>
2001-12-18 11:06 PST
Please respond to ADSM: Dist Stor Manager
To:ADSM-L AT VM.MARIST DOT EDU
cc:
bcc:
Subject:Re: Incremental forever -- any problems?
I agree with Wanda. Any kind of modern library and tape technology adds
very little time to the restore. WELL, ok, the costly ones, anyway. My 1TB
NT fileserver (I know, I know) lives on 99 primary pool tapes right now.
Collocate=filespace, so I'll be doing 3 restores at the same time, assuming
even distribution, and assuming every tape must be mounted during the
restore, that's about 33 mounts per filespace, or, assuming a 60 second
mount, an additional half hour due to mounts. I'm willing to bet that's not
my bottleneck. STK 9840, STK Powderhorn 9310 (6000 slot library), ACSLS 6
(library manager), DTELM 6.1 (external library manager for TSM to talk to)
I can really see no point in doing full backups except to give management a
warm fuzzy and justify buying more network.
How about the rest of you? What mount times are you seeing with your
libraries and how many tapes does your largest box live on? SHOW
VOLUMEUSAGE NODENAME is a quick way to eyeball it. It's an unsupported
command, so I assume no liability if it brings your server down.
Alex Paschal
Storage Administrator
Freightliner, LLC
(503) 745-6850 phone/vmail
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