On Sat, Feb 21, 2009 at 6:04 PM, John R Pierce <pie...@hogranch.com> wrote:
> Kay Diederichs wrote: > > hdparm -tT tests one type of disk access, other tools test other > > aspects. I gave the hdparm numbers because everyone can reproduce them. > > For RAID0 with two disks you do see - using e.g. hdparm - the doubling > > of performance from two disks. > > If you take the time to read (or do) RAID benchmarks you'll discover > > that Linux software RAID1 is about as fast as a single disk (and RAID0 > > with two disks is about twice the speed). It's as simple as that. > > > > > maybe with a simple single threaded application. if there are > concurrent read requests pending it will dispatch them to both drives. I'm waiting for a 10 hour backup to be completed before doing recovery on a server (ok recovery is a nice way to put it, truth is I gave up any hope of making the screwed LVM setup work and going to wipe/reinstall after the backup), I'll probably be able to try some tests. However, I don't know enough to do this properly. So some questions: Would running two CP command to copy 2 different set of files to two different targets suffice as a basic two thread test? Is there a way to monitor actual disk transfers from command line without having to do manual timing?
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