[PVE-User] LVM over ISCSI Bad performance

Harald Leithner leithner at itronic.at
Wed Jun 22 10:34:26 CEST 2016


Hi,

thank you for pointing this out for me.

Also thanks an Marco for the forum Link, a wiki update would be a real 
good idea. I tried to request an account but was unable to solve the 
"confirmation code"?!

@the multipathing topic to restore vms, I restored a VM without and 
problems.

thx

Harald



Am 22.06.2016 um 08:44 schrieb Sebastian Gruner:
> Hi, you have to create a physical volume for each LUN
>
> Pvcreate /dev/dm-0
> Pvcreate /dev/dm-1
>
> Then you can create a volumegroup
>
> Vgcreate groupname /dev/dm-0
>
> And extend the group with the second volume
>
> Vgextend groupname /dev/dm-1
>
> After that you can mount the lvm group aus storage in webinterface
>
>
>
>
> ###############################################################
> Hi again^^,
>
> I miss interpreted the benchmark result, with writeback cache is 5500 MB/s so thats ok... with direct IO it gets about 100 MB/s
>
> But I have still no clue how I could use multipath with proxmox web interface.
>
> regards,
>
> Harald
>
> Am 21.06.2016 um 19:15 schrieb Harald Leithner:
>> Hi,
>>
>> I have a MSA2312 connected with 1gbit to a 3 node PVE 4.2 Cluster.
>> I managed to get ISCSI and LVM working and attached it to a VM.
>>
>> Atm I didn't manage to get multipath working with PVE because the
>> Wikipage tells me how to create multipath (which works) but not how
>> PVE uses it for LVM VGs... maybe someone give me a hint.
>>
>> Anyway the main problem is that fio only gives me a read performance
>> of
>> 5 mb/s if I attach a disk as virtio or scsi device with cache "Writeback".
>>
>> If I attach the same SAN Drive directly in the VM with iSCSI (with and
>> without multipath) I get about 112 MB/s.
>>
>> I also get this speed on the pve host.
>>
>> I use:
>>
>> fio --filename=/dev/sdb --direct=1 --rw=read --bs=1m --size=20G
>> --numjobs=200 --runtime=60 --group_reporting --name=file1
>>
>> for benchmarking.
>>
>> While benchmarking the VM I see 1300% cpu usage on the host (mainly
>> sys
>> time)
>>
>> Maybe someone has a idea?
>>
>> regards
>>
>
> --
> Harald Leithner
>
> ITronic
> Wiedner Hauptstra├če 120/5.1, 1050 Wien, Austria
> Tel: +43-1-545 0 604
> Mobil: +43-699-123 78 4 78
> Mail: leithner at itronic.at | itronic.at
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-- 
Harald Leithner

ITronic
Wiedner Hauptstra├če 120/5.1, 1050 Wien, Austria
Tel: +43-1-545 0 604
Mobil: +43-699-123 78 4 78
Mail: leithner at itronic.at | itronic.at



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