mehr@polygon.UUCP (Mark Ehr) (03/23/88)
I have a DEC MicroVax II, which (unfortunately) has the TK50 cartridge tape drive as its' only means for backup. I am having *terrible* performance with dump (I have 4.3 BSD, by the way); as an example, I can generally only get around 35 megabytes on the tape; DEC's specifications say that it is a 90+ megabyte capacity cartridge. If anyone has any experience with this particular problem, I would very much like to hear if a fix has been found. The driver that I am using in the dump command is '/dev/rmt8', which is supposed to be the correct one. Mark Ehr @ Polygon Network, Inc. (uunet!polygon!mehr)
carson@tron.UUCP (Dana Carson) (03/24/88)
In article <160@polygon.UUCP>, mehr@polygon.UUCP (Mark Ehr) writes: > I have a DEC MicroVax II, which (unfortunately) has the TK50 cartridge tape > drive as its' only means for backup. I am having *terrible* performance > with dump (I have 4.3 BSD, by the way); as an example, I can generally > only get around 35 megabytes on the tape; DEC's specifications say that it > is a 90+ megabyte capacity cartridge. > Mark Ehr @ Polygon Network, Inc. (uunet!polygon!mehr) I know that under Ultrix 1.2 vs. 2.0 there was a big improvement by going to more buffers for streaming. The problem is that if data doesn't come in fast enough the tape controller will pad with 0s to keep the tape streaming. It will do this for a while and then give up and backup to where real data left off. If you are just slow enough that you send the next data buffer before it gives up you use up a lot of tape with padding. -- Dana Carson Westinghouse
dave@wor-mein.UUCP (Dave Axness) (03/24/88)
You didn't specify the dump command line that you are using. I suspect
that you are not using the correct paramaters for a TK50. We're still
running Ultrix 1.2 on our uVAX II and use the following:
dump 0unsdb 1200 6250 60 {partition}
Using this I get a little less than 80 Mb on a tape. Before specifying a
blocking factor, check to make sure that your version of restore will
handle blocking factors other than the default ( 10, I think ). I had
to obtain a special version from my local DEC office to support this.
Good Luck.
Dave Axness
Quantum Medical Systems
Issaquah, WA
uunet!wor-mein!dave