Quoting Paul E Condon ([email protected]): [...] > Some time ago I decided to a make a copy of these data, > so I would have more than one copy. [...] Is the copying between a USB disk and an internal, or between two partitions on the same USB disk, or between two USB disks? (Ranked in decreasing reliability in my own experience.)
> When I tried, the job would always crash well before completion. What are the symptoms of a crash? (Hang, segfault, write-failure as readonly, etc) [...] > But in both cases the > deletion failed because 'gfx2' has been remounted read-only, which > makes it impossible to update the target directory tree. Do you watch /var/log/kern.log which this is going on. I find that quite useful. For example, messages like usb 1-8: reset high-speed USB device number 5 using ehci_hcd are accompanied by a pause of anything up to a minute in file transfer. I get these quite frequently if I do massive copies between two USB disks, so I now stage such copies through the internal disk. I'm not so unlucky as Bob appears to be (he says, touching wood), but I do get occasional I/O errors on USB transfers, which can make the disk readonly, but sometimes make it disappear altogether (ie it gets unmounted, not remounted). > I have not tried it, but from my investigation I'm sure that a > massive delete of some obsolete file structure from the HD that > was /dev/sda1 during Debian install would trigger a remount-ro, > which surely would lead to a system crash in short order. You get streams of error messages (like when the disk fills up) but it shouldn't actually crash. (OTOH when you get a kernel error, there can be circumstances where the system will panic and *not* sync/write to the disk because to do so could cause corruption.) [...] > I'm worried about what I found. I want to interest someone who has far > more knowledge about how the kernel actually works internally to look > into this. I done other experiments more complicated to report, I can't > find anything comforting about this situation. If you think it's OK, > you probably don't understand, IMHO. My prejudices, based on no more than observations of my system, make me, like Bob, suspect the interface rather than the kernel. My wife, running windows, sees similar external symptoms (pauses, errors), though neither of us would know how to observe them in like manner to linux. Just in passing, if clamav wakes up and spots the USB drive, file transfers can stop for 10 or 15 minutes; the USB disk heads will still be very active. I keep an xterm running top so I can spot that (and other cpu-guzzlers like xulrunner). Oh, and to David C, this happens irrespective of wheezy or jessie (for me). Cheers, David. -- To UNSUBSCRIBE, email to [email protected] with a subject of "unsubscribe". Trouble? Contact [email protected] Archive: https://lists.debian.org/[email protected]
