Messages in this thread | | | Date | Fri, 13 Nov 1998 09:42:41 +0100 (MET) | From | Riccardo Facchetti <> | Subject | Re: e2fsck... |
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On Thu, 12 Nov 1998, Theodore Y. Ts'o wrote:
[...] > Multics did allow on-line salvaging of volumes, and it is theoretically > possible to do such a thing. But it requires that the filesystem > checker lock out kernel changes, and the filesystem checker would have > to be in close communication with the kernel while it went about its > business. E2fsck and the kernel both don't have the necessary > infrastructure to do this today.
I recall that recently someone (I don't remember who just right now) proposed some sort of snapshot device for filesystems. So that when you access a snapshot you lock the filesystem and you can backup it. The changes to the fs are recorded in a temporary partition (raw or e2fs or the-same-as-the-shapshotted ?) and the /dev/sda1snapshot is synced, locked and ready for backup (may be umounted ? Hmm ... I think better remounted readonly). This way you can even 'e2fsck /dev/sda1snapshot'. Filesystem snapshots seems a really good idea and the filesystem checker have not to be in close communication with the kernel while doing its job.
Of course this raise a lot of other problems. For example what about eating up all the temporary partition ? You have plenty of space on the real partition but the temporary one is too little and fill up very fast. The result should be a filesystem full or the kernel is allowed to allocate more space on other partitions for saving the diff data ?
Ciao, Riccardo.
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