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kuzan66
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MD3200i storage and LVM

dear all,

I have a MD3200I storage with 2 powerconnect 5524 switch and 4 R720 servers for an activ/passiv solution.

I went through iSCSI configuration and initiatiors, and I can now see the multipathed disk on each server.

In order to keep future partition size scalability, I wanted to mount these disk using LVM/

All went fine, volume group and logical disk creation based on /dev/mapper/mathb, 

I created a ext4 filesystem, and was able to create files on it.

But after reboot, all the virtual volume created and group dispareared.

looks like normal, as the system need first to boot up, then connect to iscsi in order to have the disk available, but how can I save and use the lvm created so they are mounted ?

I'm looking here for some inputs on the best way to stop and start the system without loosing the configuration.

/etc/fstab could not work, as logical disk are not yet mounted when host boot up.

DELL owner manual DM3200i documentation give some few inputs about how to stop  the system,

like umount, multipath -stop, multipath -F and iscsiadm logout,

but nothing in how to configure start up, and even on using the MD virtual disk into a LVM..

maybe a cluster??

thanks for support.

Vincent

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2 Replies
Dev Mgr
6 Gallium

RE: MD3200i storage and LVM

First; are you trying to have some or all of these 4 servers share the same disk? If so, you need to cluster the servers and this may require using a different filesystem (e.g. GFS).

Golden rule of SAN: 2 or more servers cannot share disk access to the same LUN/Volume/Virtual Disk unless there is some kind of access control management in place to allow 1 server at a time to write and notify the other servers of the changes.

If each of your servers has its own virtual disk, or you are running a cluster solution (e.g. Red Hat's Cluster Services), then this part is irrelevant.

Member since 2003

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kuzan66
1 Nickel

RE: MD3200i storage and LVM

Hi,

thanks for your answer.

no, each server run it's own partition, and the partition shall be unmounted, and mounted on another server in case of failover.

i'll simplfy my case:

I have 2 application server with 2 different application,

each server as 1 partition to mount:

serverAPP1  /data1

serverAPP2  /data2

Goal, in next futur will be to clusterise both server in failover mode,

i mean, allow both APP1 and APP2 run on a single server, in case one server crash.

the 2 partition are independant, jsut I need to be able to mount the partition on any server.

so to be abble to mount both data1 and data2 one each leg, I have configured MD3200i 2 virtual disk APP1 LUN2 and APP2  LUN3 and allow the 2 server (host) to access toit in MD3200i GUI.

I have now on the server 2 multipath drives /dev/mapper/mathb and mathc when i do fdisk -l.

I decided to use mathb as /data1 and mathc as /data2, bnut maybe my misqake is here?

I created volume group on serverAPP1, volumegroup_vg_data mounted it on /data1, created a file, updated etc/fstab,

but after reboot, fstab was wrying missing device.

here is my exact case

I'll do the same for a mysql cluster with the 2 other server and 2 partition DB.

hope it's more clear then.

vince

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