Richard Fish wrote: > Alec Shaner wrote: > > >>Once the buffer fills up would you expect it to work fine at 1.2MB/s? I >>wish I had kept the logs, but it was extremely slow (much slower than >>1.2). I was copying a series of ~70MB files over and it would work fine >>on about the first 5 or so files before croaking. I eventually had to >>kill the job. >> >> > > > From this, I'm guessing your machine has about 512MB of memory. > > The precise behavior I would expect is: > > The first 350-450MB of files (5-6 at 70MB each) would read at the speed > the filesystem/disk can provide them...in this case it seems about > 11MB/sec. So reading the first few files will take 30-40 seconds. At > this point, the USB disk will only have written 30-40 MB to > disk...leaving 300-400MB left to go. The userspace program (rsync,cp?) > at this point will basically stop writing for the next 5 to 7 _minutes_. > > In other words, you will not see nice smooth transition from 11MB/sec > down to 1.2MB/s. It will burst at high-speed for several seconds, then > stop for an extended period of time, before resuming again.
Ah, that makes sense. The system has 2GB of memory, but what you describe is very similar to what I observed. > > This of course assumes that there are no hardware problems involved. > You may want to check your /var/log/messages file or dmesg output for > any timeout or other disk errors being reported during the copy > operation. The kernel's reaction to a communication error with a disk > is to reset the controller and retry the command. I'm not sure if there > is an eventual timeout to this process or not...if there is, it is > larger than my personal 'patience timeout'! ;-> > > -Richard > > > I dug around the archived syslog files and found this snippet in there: Jun 3 15:41:04 scream kernel: SCSI device sdb: 312581808 512-byte hdwr sectors (160042 MB) Jun 3 15:41:04 scream kernel: sdb: assuming drive cache: write through Jun 3 15:41:04 scream kernel: /dev/scsi/host2/bus0/target0/lun0: p1 p2 p3 p4 Jun 3 15:41:06 scream kernel: SCSI device sdb: 312581808 512-byte hdwr sectors (160042 MB) Jun 3 15:41:06 scream kernel: sdb: assuming drive cache: write through Jun 3 15:41:06 scream kernel: /dev/scsi/host2/bus0/target0/lun0: p1 p2 p3 p4 Jun 3 15:48:16 scream kernel: SCSI error : <2 0 0 0> return code = 0x70000 Jun 3 15:48:16 scream kernel: end_request: I/O error, dev sdb, sector 47188047 Jun 3 15:48:16 scream kernel: Buffer I/O error on device sdb1, logical block 47187984 Jun 3 15:48:16 scream kernel: lost page write due to I/O error on sdb1 Jun 3 15:48:16 scream kernel: SCSI error : <2 0 0 0> return code = 0x70000 Jun 3 15:48:16 scream kernel: end_request: I/O error, dev sdb, sector 47188048 and so on.... -- gentoo-user@gentoo.org mailing list
