Fastest way to do incremental backups

[UlyssesOfEpirus]

A normal incremental backup would copy an entire .vmdk even if only a few bytes change so it is probably a bad idea. A backup with rdiff-backup would work out the deltas instead to save space, but still it would take too long because the entire .vmdk would be read.  An network backup from inside the guest to the host might be faster.  But gigabit networking much slower than today's sata drives so it would perform poorly.  The vmdk mount tool might be faster but a windows host cannot mount linux partitions with this tool (is there another? ).

What is the fastest way to do incremental backups of VM's to an external sata drive?

[RDPetruska]

"The vmdk mount tool might be faster but a windows host cannot mount linux partitions with this tool"

Have you tried it if you install one of the Linux filesystem drivers on your windows host? (http://www.fs-driver.org/ as one example)

[UlyssesOfEpirus]

Tried Ext2IFS already, it does not work with vmware-mount.exe.  What else is there?

[RDPetruska]

hmmm... ext2fsd is another one...  http://www.ext2fsd.com/

[continuum]

> A normal incremental backup would copy an entire .vmdk even if only a few bytes change so it is probably a bad idea.

did you consider to use split disks ?
copying only the chunks that changed may change the scenario ?

[JDlugosz]

Set a snapshot.

This keeps the original, large, virtual disk file unchanged, and changes go to a delta file.

The daily backup doesn't keep recopying the unchanged main file, and copies only the delta file.

[UlyssesOfEpirus]

The snapshot method sounds good but does it affect performance in normal use?

Just found ext2ifs allows the mounting of ext3 disks in windows using vmware-mount.exe! It is a read-only mount, but seems fine for backup purposes.

Remains to be seen how this mount performs compared to snapshots.  Do I have to manually go to all running VMs and take snapshots?

(Btw, splitting the disks is probably not an option because it would require some effort to go to all VM's and duplicate their disks into split .vmdks, and maybe performance during normal VM use might be affected a bit. EDIT: the dates unfortunately are the same on all pieces so all will get scanned so no gain.)

[continuum]

there is no performance loss with split preallocated disks - on the contrary - often one piece vmdks in practice are split in more fragments than a split vmdk.
The 2 Gb slices can be defragmented even on full filesystems .. so it is easier to keep split vmdks in good shape

using snapshots will affect performance much more

[UlyssesOfEpirus]

Alright but check out the EDIT above, all pieces have the same date unfortunately.

[continuum]

can you check if the size of the slice has changed and not use the date to decide which file to copy ?

[UlyssesOfEpirus]

Seems unlikely with rdiff-backup - let us not forget general backup software does not know about .vmdk but all it knows is that identical size files can differ in the content.  But this vmware-mount tool seems great now that it can read linux disks from windows.

Does anyone know how to mount several partitions from one .vmdk as different drive letters? Ideally automatically chosen drive letters? Or even without any drive letters but junction'ed from an ntfs file system?

[continuum]

to mount several partitions from a monolithicFlat I use iSCSI.
A flat.vmdk renamed to flat.img can be used as an Iscsi-target with Starwind iSCSI-server.
Next I mount the iSCSI-target with Starport or Windows builtin iscsi-initiator.
Once mounted you could use a batch with diskpart

a pity that this does not work with other formats

[admin]

You can use AutoProtect to do incremental backups. Though I'm sure continuum will not be too happy to hear this To make him happy, I'll call it Snapshot Timer. You can set WS to take a snapshot of your VM at some fixed frequency. The snapshots are essentially an incremental diff.

[continuum]

Hehe - I recently changed my mind regarding AutoProtect.

Since a few weeks I work for a VMware Consulting Company and desaster recovery is my daily business.
Now every autoprotect user is a potential future customer.
I love this feature

[UlyssesOfEpirus]

Does taking a snapshot mean duplicating the deltas ? If yes, is it a duplication of all the deltas since the first boot, or just the deltas since the last snapshotting?