Backup methodes

[Bakul Shah]

Thomas Hurst <tom.hurst at clara.net> writes:
> * Carlos Silva aka |Danger_Man| (full-disclosure at csilva.org) wrote:
> 
> > what is the best method to backup network information and local disk
> > information with another disk?
> 
> dump/restore performs snapshotted incremental backups of complete
> filesystems.

I have been using venti from plan9ports (a set of plan9
programs ported to unix like OSes) for the past few months
now.  See http://swtch.com/plan9ports

Features:
- backup ufs1 and ufs2 over the net to a venti server

- Initial full backup seems faster than dump's level 0 backup
  (I get about 3 to 7 MBps to a USB2 disk).

- Saves only one copy of every distinct block no matter
  which file it belongs to or how many times you give it to
  venti => less filling, more nutricious!

- Every backup is a full backup but because of the above
  feature venti stores only changed or new blocks.  This
  incremental backup works at close to max disk speed.  (I
  can backup a 30GB filesystem  in under 25 minutes to a USB2
  disk).  Speed of the disk being backed up is the bottleneck
  so you can simulteneously backup multiple disks to utilize a
  venti server's full disk/net bandwidth.  This is fast enough
  that backing up everything every night actually works!

- each backup returns a single `score'.  This serves
  as a handle to grab the same backup later on.

- you can nfs mount the backups.  *every* snapshot is
  available.  For example, /dump/my-host/2005/1105/usr.

- you can ftp browse a specific backup by giving its score.

- You can recreate the image of a partition as per a
  specific backup.  For instance 'vcat <score> > /dev/da0s1e'
  will recreate a specific disk image.  You can then mount it
  just like a normal disk partition.  Though I'd much prefer
  it if md(4) did this as then it can fetch data on demand.
      mdconfig -a -t venti -v <venti-server> -s <score>

It still has some warts (for example its security model
doesn't quite work well for a full restore and you have to
resort to vcat) but overall it has been a vast improvement
over dump/restore for me. venti can also be used back up file
trees like tar does.  Venti is close to a Ginsu knife of
archiving:-)

-- bakul