scott@boake2.UUCP (Scott Boake) (03/30/89)
Howdy! I was just wondering of anyone else has seen this problem.... Intel 386 16Mhz Archive Tape Drive sometimes (most?) when you go to open the /dev/rct0 device, it comes back with a "system to busy for efficient tape use" error message. Have you seen this? Backgroup: This machine was running for about 2 years before I upgraded it to SCO Xenix 386 2.3.1 (it was running SCO Xenix 286 2.2.x) and every thing was fine. After this upgrade is when the problems started. I could not run the Trailblazer modem to work while the printers where running (droping characters / timming out), tape performance was poor at best - when it didn't bomb! Upon checking the system out, I found that turning the printers off while the modem / tape drive was running resulted in a HUGE increase in performance. By watching vmstat, I came to the conclusion that this had to be due to the interrupts generated during printing. So installing a smart serial card reduced the number of interuppts from 100-150 per 10 seconds to 5-15 per 10 seconds. (printers only running - both parallel ports) But I'm still getting the above error message! With the system in multiuser mode, nothing else running except for tar, quite often when you change / insert a tape, you will get the message "system to busy for efficient tape use", and the open for /dev/*ct* failed. The error is comming from the device driver. Arrrrgh! I've tried changing the size of the tape buffer (as suggested by SCO) and all that accomplished was altering the throughput. It has no effect on this error message. You may get this error 3 - 4 times in a row and then it will take on the 4 or 5 th try. It may take on the second try... it may not take at all! (I've found the perfect random number generator :-) ). The frustrating part is when a customer calls to tell you that when they placed tape 8 (could have been 2, 3, 4, etc) of a 12-15 tape backup in the drive, it bombed with this error.... Sigh.... Any comments / suggestions ? ---Scott Scott Boake Small Systems Consulting scott@boake2 P.O. Box 2142 ..!uunet!pdn!boake2!scott 5030 - 78th Ave North Ste. 10 +1 (813) 544 - 8152 Pinellas Park, FL 34664
rosso@sco.COM (Ross Oliver) (04/01/89)
In article <261@boake2.UUCP> scott@boake2.UUCP (Scott Boake) writes: > >sometimes (most?) when you go to open the /dev/rct0 device, it comes back >with a "system to busy for efficient tape use" error message. Have you >seen this? When the tape driver opens the device, it tries to grab a large number of _contiguous_ disk buffers (128K worth, I think). If there is or has been recently a large amount of disk activity, the driver may not be able to get as many buffers as it wants. That is the cause of the error message. You can usually clear it up by doing a "sync," which write to disk and release all of the dirty but unallocated disk buffers. If that still doesn't work, you may need more disk buffers. Use configure(ADM) to increase the MAXBUF parameter. Ross Oliver Software Support Engineer The Santa Cruz Operation, Inc.