On Tue, Oct 16, 2018 at 9:42 AM, Austin S. Hemmelgarn <ahferro...@gmail.com> wrote: > On 2018-10-16 11:30, Anton Shepelev wrote: >> >> Hello, all >> >> What may be the reason of a CRC mismatch on a BTRFS file in >> a virutal machine: >> >> csum failed ino 175524 off 1876295680 csum 451760558 >> expected csum 1446289185 >> >> Shall I seek the culprit in the host machine on in the guest >> one? Supposing the host machine healty, what operations on >> the gueest might have caused a CRC mismatch? >> > Possible causes include: > > * On the guest side: > - Unclean shutdown of the guest system (not likely even if this did > happen). > - A kernel bug on in the guest. > - Something directly modifying the block device (also not very likely). > > * On the host side: > - Unclean shutdown of the host system without properly flushing data from > the guest. Not likely unless you're using an actively unsafe caching mode > for the guest's storage back-end. > - At-rest data corruption in the storage back-end. > - A bug in the host-side storage stack. > - A transient error in the host-side storage stack. > - A bug in the hypervisor. > - Something directly modifying the back-end storage. > > Of these, the statistically most likely location for the issue is probably > the storage stack on the host.
Is there still that O_DIRECT related "bug" (or more of a limitation) if the guest is using cache=none on the block device? Anton what virtual machine tech are you using? qemu/kvm managed with virt-manager? The configuration affects host behavior; but the negative effect manifests inside the guest as corruption. If I remember correctly. -- Chris Murphy
