Tape backup performance on 386 ISA/EISA systems

Conor P. Cahill cpcahil at virtech.uucp
Thu Jun 7 06:59:39 AEST 1990

A while back I posted a request for performance data on miscellaneous 
tape drives available for 386 systems.  That request got turned into 
a battle over the effectiveness of disk defragmentors and I didn't get
many responses that had actually ran the test.

So, again I am asking you to run the following test.  I am not asking you
to de-fragment you disk, nor do anything special but time a backup of
at least 30MB to tape.  I would especially like info from those of you that
have DAT, 9-track, 8mm, and cartridge tapes with >150MB capacity.

So, here is the request: 

I am trying to collect data on the performance of the different tape
backup systems available for 386 bases Unix systems.  What I am
trying to obtain is the speed in MB/minute of backing up a file system
to tape.  In order to be meaningful, the file system must be at least
30MB and be backed up using the following command (so that everybody
uses the same mechanism):

	/bin/time sh -c "find . -print | cpio -oBcC 10240 > /dev/rmt0"

Note that you may adjust the block size (10240) as you feel is appropriate
for your system as long as you tell me what you used.  Obviously you might
also need to change the tape device name.

I would like results for any tape drive you got out there including 1/4",
9-track, DAT, 8mm, etc.

If you do run the test please send me the following info:

	Tape drive:
	Disk Drive & controller:
	Size of file system:

For example on my system it would be filled in as follows:

CPU:		33Mhz 80386
Tape drive:	Archive 60MB 1/4" Cartridge
Disk info:	CDC Wren VI (676MB) w/DPT ESDI Controller with 2.5MB cache
OS:		386/ix 2.0.2
Command:	/bin/time sh -c "find . print | cpio -oBcC 10240 > /dev/rmt0"
Time:		Real: 10:50.7 	User: 10.2	System: 1:17.9
FS size:	87472 blocks (reported by du -s .)

Which turns out to be a rate of around 4.03 MB/Minute (not much of a screamer).

Please run the test when there is essentially no load on the system so that
the tests will be run under the same conditions (i.e. running the test while
you are un-batching news will have a significant detrimental effect on the
performanc and thereby give bad figures for your tape drive).

Email or post your results as you feel fit.  I would recommend emailing them
to me and I will post the results after a couple of weeks.

Thanks in advance.	

Conor P. Cahill            (703)430-9247        Virtual Technologies, Inc.,
uunet!virtech!cpcahil                           46030 Manekin Plaza, Suite 160
                                                Sterling, VA 22170 

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