On Saturday 02 September 2006 16:21, Phil Howard wrote:
> It would not need to be separate for each OS.  The idea of using a
> partition table isn't even the only approach.

The tradeoff here is that if you don't use real partitions, then you (again) 
need this tool for restore. At present the only thing you need for restore is 
gzip and tar or dump. Even with raw partitions, that would continue to be the 
case, but as soon as you introduce an Amanda-specific blocking format, that 
would no longer be the case. Performance advantages might make that 
worthwhile, but then again the same effort applied elsewhere could probably 
yield equal improvements without the sacrifice.

> FYI, I was benchmarking some disk writing for an unrelated purpose
> yesterday and found that in Linux 2.6 using the O_DIRECT option when
> opening a device to write on a disk raw (even a partition) results in much
> faster writing. Writing raw already beats writing through a filesystem. 
> Raw with O_DIRECT is much faster than raw without.  If someone does decide
> to write a driver for raw disk support, I suggest having its implementation
> test for support for the O_DIRECT option, and use it where possible.  It
> does have some size, offset, and alignment requirements that vary by OS.

This is an interesting idea, and certainly worth pursuing. I'd be interested 
in seeing your data.

--Ian
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