--- On Sun, 11/9/11, Martin Steigerwald <Martin@xxxxxxxxxxxx> wrote: > Cc to BTRFS mailinglist as it > triggered the idea of mine again. > > > Hi! > > Today I did it again and removed a BTRFS partition that is > written too. > That BTRFS as of Kernel 3.0.3 (debian package) does not > like very much. I > think thats a known issue and I wrote a mail to BTRFS > mailing list about > it. > > In there I wrote: > > > Expected results: > > > > BTRFS fails gracefully except the loss of data from > writes in flight, the > > machine remains usable and BTRFS can be mounted > again. > > And then cause the expected results IMHO are by no way the > ideal results: > > > > Ideal results (IMHO): > > > > Linux behaved like AmigaOS and told me that I *must* > insert the device > > again and *continues* writing after I did this. > > But I never saw any other OS that did that. > > And I see the problems with high bandwidth writes piling up > in memory > causing severe memory pressure. > > But then could Linux just freeze processes that continue > writing to the > drive until it is replugged again? Of course that > shouldn´t happen to the > drive / resides on. > > And there is a userspace part in it - the possibly udev and > dbus driven > notification to the user. How do you cope with (1) headless systems (one where there is no udev/dbus notification or display). (2) the user walking off in a hurry and never seeing the notification? Should the kernel/user processes freeze indefinitely? There is also a 3rd scenario - how how one malicious person or process doing a repeat insert/remove/write and get resource to pile up and crash the machine? It is probably possible/recommended with Amiga because Amiga is seldomly run headless? > > Yet despite all of this NetBSD has a gsoc 2011 project at > least suggested > for exactly this behavior: > > Graceful USB disk detach/reattach > http://wiki.netbsd.org/projects/gsoc_2011/disk-removal/ > > They even mention the Amiga in there. > > Okay, its only for USB, not for eSATA, but I think it > should be made > generic for removable devices. > > Would that be possible? I gladly file an enhancement > request about it or > help testing it. > > I think thats the only approach that makes sense here. USB > sticks and > harddisks have no means to disallow device removal at any > time. Thus the > OS should offer the user a way to rethink the decision and > plug the device > in to prevent data loss. Actually I am surprised that no > other operating > system except AmigaOS seemed to offer this behavior. Well I > am not quite > sure about MS-DOS writing to disk. Maybe it even did that. > But I did not > use MS-DOS often. > > All current mainstream operating systems I know of default > to loose data > in that case. I think there is a better choice. What do you > think? Might > not be much of a server feature, but important for the > desktop. > > Ciao, > -- > Martin 'Helios' Steigerwald - http://www.Lichtvoll.de > GPG: 03B0 0D6C 0040 0710 4AFA B82F 991B EAAC A599 > 84C7 > -- > To unsubscribe from this list: send the line "unsubscribe > linux-fsdevel" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
