>> 1) I've been comparing the speed of LVM over RAID0 with striped LVM, using:
>> perl -e '$n=1900;$x="X"x(1024*1024);foreach $i(1..$n){print $x}'
>> and I find that striped LVM takes 50% longer.
> which stripe size did you use?
I don't think I specified -- so "the default" ?
> Were the PVs on non-saturated pathes?
What are "non-saturated pathes" ?
There were two PVs, each on an otherwise unused IDE bus.
> Did you compare LVM1 Raid0 to MD Raid0 on the very same hardware?
Yes.
>> 2) When I tried to extend the striped partition, it failed when it used up
>> the first two PVs, and will not start the next two. Ideas ?
> That's a LVM1 constraint which will disapear with LVM2.
:-(
Is there an introductory document on device-mapper ?
> No need to vgexport to test it.
Hmmm ...
> Just stop one PV as you did
stop the RAID device while it's in use by LVM ?
>> b) should it be possible to export a VG if there is a PV of that VG
which
>> is still exported ?
?
>> 5) is there some utility to display the contents of VGDA on disk, /etc/lvm*,
>> etc; show where the first PE is in a PV, etc ?
> Run "pvdata -a" on the particular PV.
Where does it say "PE 0 starts at byte offset <n> of the device" ?
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