[linux-lvm] Why is my LVM Mirror performance so bad?

[Zdenek Kabelac]

Dne 27.9.2014 v 22:35 Micky napsal(a):
> Because it is LVM! :)
>

And that's what I call  'Very helpful answer'

> On Sat, Sep 27, 2014 at 10:42 PM, Errol Neal <eneal at businessgrade.com
> <mailto:eneal at businessgrade.com>> wrote:
>
>     Hi There. Hoping to get some clarity on some performance woes in a little
>     testing environment that I've setup.
>
>     I am experimenting with LVM mirrors on a CentOS 6.5 cluster.
>

Are you using  'exclusive' single node activation - or is your
mirror active on multiple nodes  with cmirrord ?



>     I have two VMs running on ESX5.5 that are sharing two RDM luns from an SRP
>     target server running SCST.
>
>     Performance however seems to take a huge hit compared to a vanilla volume
>
>
>     [root at scst1 ~]# vgs
>        VG       #PV #LV #SN Attr   VSize   VFree
>        hadata     2   5   0 wz--nc 999.99g 149.99g
>        vg_scst1   1   2   0 wz--n-  39.51g      0
>
>     [root at scst1 ~]# lvs -a -o +devices


lvs -a -o+lv_active


If you don't need cluster-wide mirror activation - use the local version:

lvchange -aey  vg/mirror


Note - new mdraid is supported only in 'exlusive' mode.

Zdenek