On Fri, 3 Feb 2023, Coly Li wrote: > > 2023年1月27日 20:44，Andrea Tomassetti <andrea.tomassetti-opensource@xxxxxxxx> 写道： > > From 83f490ec8e81c840bdaf69e66021d661751975f2 Mon Sep 17 00:00:00 2001 > > From: Andrea Tomassetti <andrea.tomassetti-opensource@xxxxxxxx> > > Date: Thu, 8 Sep 2022 09:47:55 +0200 > > Subject: [PATCH v2] bcache: Add support for live resize of backing devices > > > > Signed-off-by: Andrea Tomassetti <andrea.tomassetti-opensource@xxxxxxxx> > > --- > > Hi Coly, > > this is the second version of the patch. As you correctly pointed out, > > I implemented roll-back functionalities in case of error. > > I'm testing this funcionality using QEMU/KVM vm via libvirt. > > Here the steps: > > 1. make-bcache --writeback -B /dev/vdb -C /dev/vdc > > 2. mkfs.xfs /dev/bcache0 > > 3. mount /dev/bcache0 /mnt > > 3. dd if=/dev/random of=/mnt/random0 bs=1M count=1000 > > 4. md5sum /mnt/random0 | tee /mnt/random0.md5 > > 5. [HOST] virsh blockresize <vm-name> --path <disk-path> --size <new-size> > > 6. xfs_growfs /dev/bcache0 > > 6. Repeat steps 3 and 4 with a different file name (e.g. random1.md5) > > 7. umount/reboot/remount and check that the md5 hashes are correct with > > md5sum -c /mnt/random?.md5 > > [snipped] > > Hi Andrea, > > For the above step 5, could you provide a specific command line for me to reproduce? > > I tried to resize the disk by virsh from 400G to 800G, the disk resize > doesn’t happen online, I have to stop and restart the virtual machine > and see the resized disk. Coly, The `virsh blockresize` command only informs the vm that the size has changed. You will need to resize the disk itself using `lvresize` or whatever your VM's backing device is. If you're backing device for the virtual machine is a file, then you could use `truncate -s <size> /file/path` before issuing `virsh blockresize`. Another possibility: are you using virtio-blk as shown in his example, or a different virtual driver like virtio-scsi? If the VM doesn't detect it you might need to do this if its a virtio-scsi disk on the inside: for i in /sys/class/scsi_host/*/scan; do echo - - - > $i; done If you're using virtio-blk (vda) then it should be immediate. I don't think IDE will work at all, and not sure about nvme. -- Eric Wheeler > Thanks. > > Coly Li > >
