[linux-lvm] Allocation Policy for Cloud Computing needed
Sebastian Riemer
sebastian.riemer at profitbricks.com
Tue Feb 21 09:34:18 UTC 2012
On 20/02/12 22:59, Lars Ellenberg wrote:
>> 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.
Yes, this really helps. I've also thought about allocating the LVs
directly to distinct PVs. Thanks for the confirmation.
> 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...
Thank you very much for your response.
Regards,
Sebastian
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