Re: [pve-devel] [PATCH 00/11] live-restore for PBS snapshots

[aderumier@odiso.com]

Hi,
that's great !

I'm not sure it's related, but do you have any plan to add support to
restore/extract files from the vm filesystem directly ? 
if we could make some kind of qemu-nbd + mount loop of the backup
volume for example.


This is the main blocking feature for me, instead using my rbd
import/export for backups.

Regards,

Alexandre

Le lundi 11 janvier 2021 à 12:13 +0100, Stefan Reiter a écrit :
> "live-restore" allows starting a VM immediately from a backup
> snapshot, no
> waiting for a long restore process. This is made possible with QEMU
> backing
> images, i.e. data is read from the backup which is attached to the VM
> as a
> drive, but new data is written to the destination, while a background
> process
> ('block-stream') copies over data in a linear fashion as well.
> 
> QEMU backing images are normally only supported for qcow2 images, but
> since the
> destination always starts out empty, we can use a dirty bitmap to
> achieve the
> same effect - this is implemented as the 'alloc-track' driver in the
> 'qemu' part
> of the series.
> 
> The Rust part of the equation is adjusted to provide (quiet a lot)
> more caching,
> as mixing random read/write from the guest with the linear reads from
> the
> background process (both of which may use read sizes smaller or
> bigger than a
> single chunk) would thrash performance without large buffers.
> 
> I've marked the feature as 'experimental' in the GUI for now, as I'm
> sure there
> are a lot of edge cases I've missed to test, and there's also the
> possibility of
> data loss, since anything the VM writes during the restore is removed
> if the
> restore fails.
> 
> 
> qemu: Stefan Reiter (3):
>   PVE: explicitly add libuuid as linking dependency
>   PVE: block/pbs: fast-path reads without allocation if possible
>   block: add alloc-track driver
> 
>  Makefile.objs       |   2 +
>  block/Makefile.objs |   1 +
>  block/alloc-track.c | 319
> ++++++++++++++++++++++++++++++++++++++++++++
>  block/pbs.c         |  17 ++-
>  4 files changed, 336 insertions(+), 3 deletions(-)
>  create mode 100644 block/alloc-track.c
> 
> proxmox-backup: Stefan Reiter (1):
>   RemoteChunkReader: add LRU cached variant
> 
>  src/bin/proxmox_backup_client/mount.rs |  4 +-
>  src/client/remote_chunk_reader.rs      | 77 ++++++++++++++++++++----
> --
>  2 files changed, 62 insertions(+), 19 deletions(-)
> 
> proxmox-backup-qemu: Stefan Reiter (1):
>   access: use bigger cache and LRU chunk reader
> 
>  src/restore.rs | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> qemu-server: Stefan Reiter (5):
>   make qemu_drive_mirror_monitor more generic
>   cfg2cmd: allow PBS snapshots as backing files for drives
>   enable live-restore for PBS
>   extract register_qmeventd_handle to QemuServer.pm
>   live-restore: register qmeventd handle
> 
>  PVE/API2/Qemu.pm         |  15 ++-
>  PVE/QemuServer.pm        | 263 ++++++++++++++++++++++++++++++++-----
> --
>  PVE/VZDump/QemuServer.pm |  32 +----
>  3 files changed, 233 insertions(+), 77 deletions(-)
> 
> manager: Stefan Reiter (1):
>   ui: restore: add live-restore checkbox
> 
>  www/manager6/grid/BackupView.js    |  8 +++++--
>  www/manager6/storage/BackupView.js |  7 ++++--
>  www/manager6/window/Restore.js     | 38
> +++++++++++++++++++++++++++++-
>  3 files changed, 48 insertions(+), 5 deletions(-)
>