On Fri, Sep 14, 2007 at 03:22:30PM +0100, chris at darach.ie wrote:
> On Fri, Sep 14, 2007 at 12:09:35AM +0100, Conor Daly wrote:
> > I'm using dump to backup a number of filesystems to a tape hosted on a
> > remote machine. The machine being backed up is still in commissioning so
> > it hasn't got its full complement of data yet. Last night, one 300Gb
> > filesystem had about 21Gb used. It took 3.5 hours to dump at an average
> > rate of 1530 kB/s (according to dump). By my calculations, if this
> > filesystem fill completely, it will take 57 hours to backup.
> > The dump runs like this:
> > Remote machine mounts the tape
> > local machine does:
> > export RSH=ssh
>> Erm - isn't ssh chronically braindead when it comes to using it
> for this purpose ?
> > The problem is that using rsh, the transfer rate is around
> > 3,000KB/sec,
> > using ssh its only around 600KB/sec.
>> Doesn't SSH still have that internal 2k block limit ?
try these patches out for openssh to get better performance over
though i think the more recent versions of openssh have some dynamic
code to scale the block limits.
also wouldn't the number of small files be a factor in how fast you can
read the files (number of file opens and closes). I guess if you're
dumping the filesystem it shouldnt really matter.
Trinity Centre for High Performance Computing,
Lloyd Building, Trinity College Dublin, Dublin 2, Ireland.
http://www.tchpc.tcd.ie/ | http://www.tchpc.tcd.ie/~jtang
Maintained by the ILUG website team. The aim of Linux.ie is to
support and help commercial and private users of Linux in Ireland. You can
display ILUG news in your own webpages, read backend
information to find out how. Networking services kindly provided by HEAnet, server kindly donated by
Dell. Linux is a trademark of Linus Torvalds,
used with permission. No penguins were harmed in the production or maintenance
of this highly praised website. Looking for the
Indian Linux Users' Group? Try here. If you've read all this and aren't a lawyer: you should be!