Hi Tim, I recently stumbled on the same thing, accidentally shrinking a blockdevice. I have written a patch for virsh that will force the user to append a '--force' flag if shrinking is desired. The behavior is somewhat still inconsistent with the vol-resize command, however a bigger rewrite is needed to make both commands operate exactly the same, which I don't know if actually needed. Previous discussion can be found below, - https://www.redhat.com/archives/libvir-list/2019-October/msg00258.html - https://www.redhat.com/archives/libvir-list/2019-October/msg01437.html Best regards, Patrik On Thu, Oct 24, 2019 at 6:04 PM Tim Small <tim@xxxxxxxxxxx> wrote: > > Hello, > > virsh has two commands which can be used to resize block devices - > "blockresize" for volumes in use by and active guest, and "vol-resize" > for volumes which are not in use. > > The vol-resize syntax allows to specify the size as a delta (increase or > decrease vs. the current size), and also refuses to shrink a volume > unless the "--shrink" argument is also passed. > > Most other tools which can be used for block device resizing (outside of > libvirt) also have similar "--shrink" argument requirements when > reducing the size of an existing block device. e.g. ceph requires > "--allow-shrink" when using the "rbd resize" command. > > The lack of such a safety device makes "blockresize" a foot-gun (which I > recently found to great effect when I typoed the domain name to another > valid domain). > > It seems I am not alone in making this error e.g. > https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=902171 > > One possible solution would be to make a new command e.g. "domblkresize" > or perhaps "live-resize", which implement the "--shrink" and "--delta" > behaviour to make it consistent with "vol-resize" syntax, and mark the > "blockresize" command as deprecated in the documentation and help (so > that existing automation which depends on the current behaviour doesn't > break). > > Any thoughts? Should I open this as an RFE? > > Thanks, > > Tim. > > > -- > South East Open Source Solutions Limited > Registered in England and Wales with company number 06134732. > Registered Office: 2 Powell Gardens, Redhill, Surrey, RH1 1TQ > VAT number: 900 6633 53 http://seoss.co.uk/ +44-(0)1273-808309 > > -- > libvir-list mailing list > libvir-list@xxxxxxxxxx > https://www.redhat.com/mailman/listinfo/libvir-list > -- Best regards, Patrik Martinsson -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list
