How to replace Multipath by Ultrapath in Linux system.

Publication Date:  2012-09-20 Views:  1586 Downloads:  0
Issue Description
When Linux system connects Huawei system storage, we must use Ultrapath multipathing software. If the multipathing software is Multipath which comes from customer system, we must uninstall it first.
Alarm Information
Null
Handling Process
1.Record the mount points of all disk device. Preserve the export messages from fstab,df -h and mount.
2.Compare ll /dev/mpath/mpath* and multipath -ll. Find the relationship between mpath* and its corresponding storage LUN as follow:
/mountdir -> (mpath1p1 -> dm-10) -> mpath1 -> dm-1 -> LUN2
3.Forbid Multipath multipathing software. Delete the content of /etc/multipath.conf except following 3 lines:
blacklist {
devnode "*"
}
There are no above 3 lines as usual after using Multipath. If Forbidding Multipath, please resume above 3 line.
4.Delete current directory and reloading Multipath multipathing. Check it effect or not.
multipath -F  //Delete current Multipath directory.
service multipathd reload // Reloading Multipath multipathing
multipath -v2   //Check whether the multipath directory exists.
5.Forbid Multipath self-starting. Modify fstab and reboot.
chkconfig multipathd off
init 6
6.Insure no multipathing information by command “multipath –ll”. Delete Multipath information by command “dmsetup remove_all”.
7.Install Ultrapath multipathing software and reboot. Modify fstab starting auto-mount directory as mapping.
Root Cause
When managed by Multipath , the disk device will appear at 3 positions: /dev/mapper/mpath*、/dev/mpath/mpath*、/dev/dm-*. With command fdisk –l we can find them.
Suggestions
Attention: Record and insure the relationship between mount point and disk LUN ID first.

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