mf@ircam.fr (Michel Fingerhut) (11/03/90)
Having had disk problems on ra90s, we had one replaced. So as to copy the file systems from the old one to the new one, we ran a dump of each fs in the old one piped into a restore on the corresponding fs on the new one. This was run in single user mode, and single jobs: nothing done in parallel. It took an incredible long time to perform: for a 500 Meg partition -- over 2.5 hours. Does anyone have a clue as to why? Disk performance, controler management of accesses to different drives, pipe problem or what? Thanks for any help, Michael Fingerhut
karrer@ethz.UUCP (Andreas Karrer) (11/04/90)
mf@ircam.fr (Michel Fingerhut) writes: >Having had disk problems on ra90s, we had one replaced. So as to copy the >file systems from the old one to the new one, we ran a dump of each fs in >the old one piped into a restore on the corresponding fs on the new one. >This was run in single user mode, and single jobs: nothing done in parallel. >It took an incredible long time to perform: for a 500 Meg partition -- over >2.5 hours. I just did that on a DECsystem 5840 (3 RA90's on one kdb50) with: /etc/dump 0f - /dev/rra1d | /etc/restore rf - /dev/rra1d is 144518 kB, 97439 used. It took 14 min 12 sec. That would make about 50 mins for your 500 Megs. Did you specify the raw device? Come to think of it - we initially had problems with partitions that were not an integral multiple of the cylinder size. You should probably check (chpt -q) if all your ra90 partitions are a multiple of 13tracks*69sectors*512bytes. DEC's defaults are set up this way. BTW, i do not think that the 14:12 are FAST - it makes about 115 kB/sec. Disk transfer rates (reported by iostat) never got higher than 247 bps, but the cpu's were only lightly loaded. If I dump to an exabyte (emulates TU81, on klesi-b vaxbi adapter), using /etc/dump 0dsf 1600 90000 - /dev/rra1d | buffer -s 126b > /dev/nrmt0h I get about 210 kB/sec, which still does not bring the tape to streaming mode. >Does anyone have a clue as to why? Disk performance, controler management of >accesses to different drives, pipe problem or what? I think the kdb50/ra90 combination is just lousy. Here some timings from copying a 10M file from one disk to another (/bin/time cp FROM TO): machine disks real sys Convex C 220 NEC D2363 VME 2.5 2.1 sec Sun 4/490 Sabre 1150 IPI 4.9 2.9 DECsystem 5840 DEC RA 90 29.0 13.4 Sun 3/280 CDC Eagle SMD 33.4 12.9 DECsystem 5400 DEC RA 90 37.3 10.5 DEC VAX 11/785 DEC RA 81 41.4 25.1 (all systems very lightly loaded). The comparison with the Convex is not fair, since it costs quite a bit more. However, the Sun 4/490 _does not_. The last line shows that the i/o performance of DEC machines did not increase dramatically over the years... >Thanks for any help, >Michael Fingerhut not much of a help - oh well... +------ Andi Karrer, Communication Systems, ETH Zuerich, Switzerland. karrer@ks.id.ethz.ch karrer@czheth5a.bitnet