Performance Storage FAQ

How to verify if MPIO is configured correctly in *NIX OSes

To check if multipath is picking up the devices, only the NETAPP devices should show up and there should be two of them. 

root@server:~# multipath -l 3600a09803830304f3124457a45757067 dm-1 NETAPP,LUN C-Mode size=20G features='1 queue_if_no_path' hwhandler='0' wp=rw |-+- policy='round-robin 0' prio=-1 status=active | `- 6:0:0:101 sdd 8:48 active undef running `-+- policy='round-robin 0' prio=-1 status=enabled `- 7:0:0:101 sde 8:64 active undef running

Check that the disks are present, and there should be two disks with the same identifier, and a /dev/mapper listing of the same size with the same identifier. The /dev/mapper device is the one that multipath sets up:

root@server:~# fdisk -l | grep Disk Disk /dev/sda: 500.1 GB, 500107862016 bytes Disk identifier: 0x0009170d Disk /dev/sdc: 21.5 GB, 21474836480 bytes Disk identifier: 0x2b5072d1 Disk /dev/sdb: 21.5 GB, 21474836480 bytes Disk identifier: 0x2b5072d1 Disk /dev/mapper/3600a09803830304f3124457a45757066: 21.5 GB, 21474836480 bytes Disk identifier: 0x2b5072d1

If it is not correctly setup, it will look like this: 

No multipath output root@server:~# multipath -l root@server:~#

This will show the devices blacklisted:

root@server:~# multipath -l -v 3 | grep sd Feb 17 19:55:02 | sda: device node name blacklisted Feb 17 19:55:02 | sdb: device node name blacklisted Feb 17 19:55:02 | sdc: device node name blacklisted Feb 17 19:55:02 | sdd: device node name blacklisted Feb 17 19:55:02 | sde: device node name blacklisted

fdisk shows only the sd* devices, and no /dev/mapper

root@server:~# fdisk -l | grep Disk Disk /dev/sda: 500.1 GB, 500107862016 bytes Disk identifier: 0x0009170d Disk /dev/sdc: 21.5 GB, 21474836480 bytes Disk identifier: 0x2b5072d1 Disk /dev/sdb: 21.5 GB, 21474836480 bytes Disk identifier: 0x2b5072d1

To ensure a proper MPIO configuration, please refer to our KnowledgeLayer Article on setting this up from Start to Finish:

http://knowledgelayer.softlayer.com/procedure/accessing-block-storage-performance-storage-linux

Will I be able to achieve more throughput if I used a faster Ethernet connection?

Throughput limits are set at a per-volume/LUN level so using a faster Ethernet connection will not increase that set limit. However, with a slower Ethernet connection, your bandwidth can be a potential bottleneck.