On Sat, Sep 02, 2006 at 06:39:40PM -0400, Jon LaBadie wrote: | Phil, | what advantage(s) do you forsee in amanda's use of raw disk | devices as opposed to files on the native filesystem.
The ability to avoid the page cached I/O subsystem to control performance impact on the system. | It certainly would destroy one of amanda's features, | the ability to easily recover backup data using | standard unix utilities without amanda software. How is that destroyed? Suppose you use tar format. You can have tar read from tape directly, which is what I presume you mean for being able to recover outside of Amanda. You can have tar read from disk partitions if the native partition scheme is used. | I've not heard people on the list reporting poor performance | in using the current scheme for saving backups on disk-based | 'virtual tapes'. If there are, I'd like to know about it. How could they have compared if there is none writing to raw disk now? | Given that the backups are coming from dump or tar, possibly | over a network, possibly processed by compression and encryption | software, it is unlikely that the final disk writing is a bottleneck. Certainly there will be situations where other factors affect the speed. | Perhaps additional features would be possible. Like multiplexed | "direct to tape" dumps without a holding disk. The current scheme | only allows a single dump direct to tape. Multiplexed dumps have | to go to a holding disk before being taped. A potential project will have some very large data. Each machine can have its own external backup drives, so for each machine it can be seen as a single dump. It's just going to be large. Probably 400G or 800G per machine. I'm just exploring all options and Amanda is one of them. If I do go with a filesystem on the disks, I'll probably use rsync so the disk is a replica and can simply substitute as is. -- ----------------------------------------------------------------------------- | Phil Howard KA9WGN | http://linuxhomepage.com/ http://ham.org/ | | (first name) at ipal.net | http://phil.ipal.org/ http://ka9wgn.ham.org/ | -----------------------------------------------------------------------------
