* [linux-lvm] Why is my LVM Mirror performance so bad?
@ 2014-09-27 17:42 Errol Neal
2014-09-27 20:35 ` Micky
` (2 more replies)
0 siblings, 3 replies; 5+ messages in thread
From: Errol Neal @ 2014-09-27 17:42 UTC (permalink / raw)
To: linux-lvm
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.
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@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@scst1 ~]# lvs -a -o +devices
LV VG Attr LSize Pool Origin Data% Move Log Cpy%Sync Convert Devices
mirror1 hadata mwi-a-m--- 100.00g 100.00 mirror1_mimage_0(0),mirror1_mimage_1(0)
[mirror1_mimage_0] hadata iwi-aom--- 100.00g /dev/sdb1(0)
[mirror1_mimage_1] hadata iwi-aom--- 100.00g /dev/sdc1(0)
mirror2 hadata mwi-a-m--- 100.00g 100.00 mirror2_mimage_0(0),mirror2_mimage_1(0)
[mirror2_mimage_0] hadata iwi-aom--- 100.00g /dev/sdb1(25600)
[mirror2_mimage_1] hadata iwi-aom--- 100.00g /dev/sdc1(25600)
mirror3 hadata mwi-a-m--- 100.00g 100.00 mirror3_mimage_0(0),mirror3_mimage_1(0)
[mirror3_mimage_0] hadata iwi-aom--- 100.00g /dev/sdb1(51200)
[mirror3_mimage_1] hadata iwi-aom--- 100.00g /dev/sdc1(51200)
mirror4 hadata mwi-a-m--- 100.00g 100.00 mirror4_mimage_0(0),mirror4_mimage_1(0)
[mirror4_mimage_0] hadata iwi-aom--- 100.00g /dev/sdb1(76800)
[mirror4_mimage_1] hadata iwi-aom--- 100.00g /dev/sdc1(76800)
test hadata -wi-a----- 50.00g /dev/sdb1(102400)
lv_root vg_scst1 -wi-ao---- 31.65g /dev/sda2(0)
lv_swap vg_scst1 -wi-ao---- 7.86g /dev/sda2(8102)
[root@scst1 ~]# dd if=/dev/sdb1 of=/dev/null bs=1M count=20000
20000+0 records in
20000+0 records out
20971520000 bytes (21 GB) copied, 41.0031 s, 511 MB/s
[root@scst1 ~]# dd if=/dev/hadata/test of=/dev/null bs=1M count=20000
20000+0 records in
20000+0 records out
20971520000 bytes (21 GB) copied, 44.344 s, 473 MB/s
[root@scst1 ~]# dd if=/dev/hadata/mirror1 of=/dev/null bs=1M count=20000
20000+0 records in
20000+0 records out
20971520000 bytes (21 GB) copied, 365.685 s, 57.3 MB/s
Is this just the life of a LVM mirror and the performance here is about as good as it gets?
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [linux-lvm] Why is my LVM Mirror performance so bad?
2014-09-27 17:42 [linux-lvm] Why is my LVM Mirror performance so bad? Errol Neal
@ 2014-09-27 20:35 ` Micky
2014-09-29 8:59 ` Zdenek Kabelac
2014-09-29 18:15 ` Linda A. Walsh
2014-09-30 3:27 ` Brassow Jonathan
2 siblings, 1 reply; 5+ messages in thread
From: Micky @ 2014-09-27 20:35 UTC (permalink / raw)
To: eneal, LVM general discussion and development
[-- Attachment #1: Type: text/plain, Size: 3038 bytes --]
Because it is LVM! :)
On Sat, Sep 27, 2014 at 10:42 PM, Errol Neal <eneal@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.
>
> 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@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@scst1 ~]# lvs -a -o +devices
> LV VG Attr LSize Pool Origin Data% Move
> Log Cpy%Sync Convert Devices
> mirror1 hadata mwi-a-m--- 100.00g
> 100.00 mirror1_mimage_0(0),mirror1_mimage_1(0)
> [mirror1_mimage_0] hadata iwi-aom--- 100.00g
> /dev/sdb1(0)
> [mirror1_mimage_1] hadata iwi-aom--- 100.00g
> /dev/sdc1(0)
> mirror2 hadata mwi-a-m--- 100.00g
> 100.00 mirror2_mimage_0(0),mirror2_mimage_1(0)
> [mirror2_mimage_0] hadata iwi-aom--- 100.00g
> /dev/sdb1(25600)
> [mirror2_mimage_1] hadata iwi-aom--- 100.00g
> /dev/sdc1(25600)
> mirror3 hadata mwi-a-m--- 100.00g
> 100.00 mirror3_mimage_0(0),mirror3_mimage_1(0)
> [mirror3_mimage_0] hadata iwi-aom--- 100.00g
> /dev/sdb1(51200)
> [mirror3_mimage_1] hadata iwi-aom--- 100.00g
> /dev/sdc1(51200)
> mirror4 hadata mwi-a-m--- 100.00g
> 100.00 mirror4_mimage_0(0),mirror4_mimage_1(0)
> [mirror4_mimage_0] hadata iwi-aom--- 100.00g
> /dev/sdb1(76800)
> [mirror4_mimage_1] hadata iwi-aom--- 100.00g
> /dev/sdc1(76800)
> test hadata -wi-a----- 50.00g
> /dev/sdb1(102400)
> lv_root vg_scst1 -wi-ao---- 31.65g
> /dev/sda2(0)
> lv_swap vg_scst1 -wi-ao---- 7.86g
> /dev/sda2(8102)
>
> [root@scst1 ~]# dd if=/dev/sdb1 of=/dev/null bs=1M count=20000
> 20000+0 records in
> 20000+0 records out
> 20971520000 bytes (21 GB) copied, 41.0031 s, 511 MB/s
>
> [root@scst1 ~]# dd if=/dev/hadata/test of=/dev/null bs=1M count=20000
> 20000+0 records in
> 20000+0 records out
> 20971520000 bytes (21 GB) copied, 44.344 s, 473 MB/s
>
> [root@scst1 ~]# dd if=/dev/hadata/mirror1 of=/dev/null bs=1M count=20000
> 20000+0 records in
> 20000+0 records out
> 20971520000 bytes (21 GB) copied, 365.685 s, 57.3 MB/s
>
>
> Is this just the life of a LVM mirror and the performance here is about as
> good as it gets?
>
> _______________________________________________
> 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/
>
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^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [linux-lvm] Why is my LVM Mirror performance so bad?
2014-09-27 20:35 ` Micky
@ 2014-09-29 8:59 ` Zdenek Kabelac
0 siblings, 0 replies; 5+ messages in thread
From: Zdenek Kabelac @ 2014-09-29 8:59 UTC (permalink / raw)
To: LVM general discussion and development, eneal
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@businessgrade.com
> <mailto:eneal@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@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@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
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [linux-lvm] Why is my LVM Mirror performance so bad?
2014-09-27 17:42 [linux-lvm] Why is my LVM Mirror performance so bad? Errol Neal
2014-09-27 20:35 ` Micky
@ 2014-09-29 18:15 ` Linda A. Walsh
2014-09-30 3:27 ` Brassow Jonathan
2 siblings, 0 replies; 5+ messages in thread
From: Linda A. Walsh @ 2014-09-29 18:15 UTC (permalink / raw)
To: eneal, LVM general discussion and development
Errol Neal wrote:
> Is this just the life of a LVM mirror and the performance here is about as good as it gets?
> ----
>
It's a bit confusing from what you have above, but *usually*, if you
want performance, you set up 1 duplicate device (disk) to duplicate another
of the same type. That way when the controller is writing to 1, it will
be able to
write to the other in the same location and expect *similar* speeds
(speeds will
vary more on desktop drives vs. enterprise, so overall RAID performance
is lost).
From what it looks like you have multiple segments mirroring other
(parallel?? not sure)
segments... but as data is being written to one segment, it also may not
have finished
writing a parallel copy to another segment.
Don't setup multiple segments mirroring each other on 2 devices... have
1 be the mirror
of the other and both be of similar type if you want near device speed.
i.e. you don't want 4 mirrors, but want to make all of sdb mirror all of
sdc.
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [linux-lvm] Why is my LVM Mirror performance so bad?
2014-09-27 17:42 [linux-lvm] Why is my LVM Mirror performance so bad? Errol Neal
2014-09-27 20:35 ` Micky
2014-09-29 18:15 ` Linda A. Walsh
@ 2014-09-30 3:27 ` Brassow Jonathan
2 siblings, 0 replies; 5+ messages in thread
From: Brassow Jonathan @ 2014-09-30 3:27 UTC (permalink / raw)
To: eneal, LVM general discussion and development
On Sep 27, 2014, at 12:42 PM, Errol Neal 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.
>
> 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@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@scst1 ~]# lvs -a -o +devices
> LV VG Attr LSize Pool Origin Data% Move Log Cpy%Sync Convert Devices
> mirror1 hadata mwi-a-m--- 100.00g 100.00 mirror1_mimage_0(0),mirror1_mimage_1(0)
> [mirror1_mimage_0] hadata iwi-aom--- 100.00g /dev/sdb1(0)
> [mirror1_mimage_1] hadata iwi-aom--- 100.00g /dev/sdc1(0)
> mirror2 hadata mwi-a-m--- 100.00g 100.00 mirror2_mimage_0(0),mirror2_mimage_1(0)
> [mirror2_mimage_0] hadata iwi-aom--- 100.00g /dev/sdb1(25600)
> [mirror2_mimage_1] hadata iwi-aom--- 100.00g /dev/sdc1(25600)
> mirror3 hadata mwi-a-m--- 100.00g 100.00 mirror3_mimage_0(0),mirror3_mimage_1(0)
> [mirror3_mimage_0] hadata iwi-aom--- 100.00g /dev/sdb1(51200)
> [mirror3_mimage_1] hadata iwi-aom--- 100.00g /dev/sdc1(51200)
> mirror4 hadata mwi-a-m--- 100.00g 100.00 mirror4_mimage_0(0),mirror4_mimage_1(0)
> [mirror4_mimage_0] hadata iwi-aom--- 100.00g /dev/sdb1(76800)
> [mirror4_mimage_1] hadata iwi-aom--- 100.00g /dev/sdc1(76800)
> test hadata -wi-a----- 50.00g /dev/sdb1(102400)
> lv_root vg_scst1 -wi-ao---- 31.65g /dev/sda2(0)
> lv_swap vg_scst1 -wi-ao---- 7.86g /dev/sda2(8102)
>
> [root@scst1 ~]# dd if=/dev/sdb1 of=/dev/null bs=1M count=20000
> 20000+0 records in
> 20000+0 records out
> 20971520000 bytes (21 GB) copied, 41.0031 s, 511 MB/s
>
> [root@scst1 ~]# dd if=/dev/hadata/test of=/dev/null bs=1M count=20000
> 20000+0 records in
> 20000+0 records out
> 20971520000 bytes (21 GB) copied, 44.344 s, 473 MB/s
>
> [root@scst1 ~]# dd if=/dev/hadata/mirror1 of=/dev/null bs=1M count=20000
> 20000+0 records in
> 20000+0 records out
> 20971520000 bytes (21 GB) copied, 365.685 s, 57.3 MB/s
>
>
> Is this just the life of a LVM mirror and the performance here is about as good as it gets?
Is the performance also degraded in this way when using single machine (i.e. not cluster)?
brassow
^ permalink raw reply [flat|nested] 5+ messages in thread
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2014-09-27 17:42 [linux-lvm] Why is my LVM Mirror performance so bad? Errol Neal
2014-09-27 20:35 ` Micky
2014-09-29 8:59 ` Zdenek Kabelac
2014-09-29 18:15 ` Linda A. Walsh
2014-09-30 3:27 ` Brassow Jonathan
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