> > Then, I've tested to put all my RAID-1 arrays into a single VG, > > because LV size should be adjustable over all hard drives. ... > > I want to have an allocation which distributes the LVs equally over > > the PVs as long as space is left and LVs aren't resized. Since you're using RAID anyway, consider testing RAID 10, which will distribute IO across spindles. > You can get pretty complex in similar scripts, if you really want > to... consider using > pvs -o vg_name,lv_name,pv_name,pvseg_start,pvseg_size,seg_pe_ranges > and explicitly listing not only the PVS, but even the PE ranges to > your lvcreate commands... For scripting, see Linux::LVM on CPAN. It gives you that information as a nice data structure. I welcome feature requests and patches. (Linux::LVM::Do coming soon for modifying rather than just querying LVM objects.) -- Ray Morris support@bettercgi.com Strongbox - The next generation in site security: http://www.bettercgi.com/strongbox/ Throttlebox - Intelligent Bandwidth Control http://www.bettercgi.com/throttlebox/ Strongbox / Throttlebox affiliate program: http://www.bettercgi.com/affiliates/user/register.php On Mon, 20 Feb 2012 22:59:11 +0100 Lars Ellenberg <lars.ellenberg@linbit.com> wrote: > On Thu, Feb 16, 2012 at 02:50:07PM +0100, Sebastian Riemer wrote: > > Hi LVM list, > > > > I'm experimenting with storage for many QEMU/KVM virtual machines in > > cloud computing. I've got many concurrent IO processes and 24 hard > > drives. I've tested the scalability with a single IO reader process > > per hard drive. Single drives scale best and have the best > > performance of cause, but we need mirroring and volume management. > > So I've created MD RAID-1 arrays and created on each a VG and two > > LVs. This gives me good overall performance (up to 2 GB/s, HBA > > limit: 2.2 GB/s). > > > > Then, I've tested to put all my RAID-1 arrays into a single VG, > > because LV size should be adjustable over all hard drives. I've > > tried all allocation policies but none does what I want to achieve > > here. Yeah, that this isn't implemented fully is in the man > > page, ... . > > > > I want to have an allocation which distributes the LVs equally over > > the PVs as long as space is left and LVs aren't resized. The goal > > is to minimize the number of concurrent IO processes per hard drive > > (striping is total crap in this situation). > > > > I've tested LVM2 2.02.66 and kernel 3.0.15. Is something like that > > implemented in newer releases or is something like that intended to > > be implemented in near future? > > I don't know. Does not look like it, though. > > > Or does someone want to implement this together with me? > > I would certainly be here for discussions. > > Though, as you always will be more flexible with scripts than with > pre-implemented fixed algorithms, I probably would first check if I > can solve it with some scripting. > [completely untested, but you get the idea] > > #!/bin/bash > export LANG=C LC_ALL=C > name=$1 vg=$2 size_in_MiB=$3 > PVS=$(vgs --nohead --unit m -o pv_name,pv_free -O -pv_free,pv_name > $vg | awk -v need=$size_in_MiB '{ print $1; sum += $2; > if (sum >= need) exit; }') > lvcreate -n $name -L ${size_in_MiB}m $vg $PVS > > (similar for lvextend) > > Which basically implements this allocation policy: > use the pvs with most free space available, > and no more than necessary. > > If I understand you correctly, that would almost do what you asked > for. > > You can get pretty complex in similar scripts, if you really want > to... consider using > pvs -o vg_name,lv_name,pv_name,pvseg_start,pvseg_size,seg_pe_ranges > and explicitly listing not only the PVS, but even the PE ranges to > your lvcreate commands... > > Lars > _______________________________________________ linux-lvm mailing list linux-lvm@redhat.com https://www.redhat.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
