CentOS adding or removing FC multipath disks without reboot

For adding LVM on top of FC we do following:

1. Rescan fc devices using

   ls /sys/class/fc_host

   and then for each host
   

   echo "1" > /sys/class/fc_host/host0/issue_lip
   echo "- - -" > /sys/class/scsi_host/host0/scan
   

   
   

2. Check for device with lun ID in /dev/disk/by-id/
3. See if multipath is working (multipath -ll or service multipathd reload)
4. Create partition on multipath device (Fdisk or parted)
5. If partition is not appearing in /dev/mapper do partprobe
6. Create physical volution (pvcreate)
7. Add physical volume to volumegroup (vgcreate etc.)
8. Create Logical volume (lvmcreate, etc.)
9. Activate volume group (vgchange -a y <volgroup>)
10. Mount the device using /dev/mapper/<volgroup>-<logvol>

For removal we need to do the opposite which is at least:

1. Get device name from /dev/disk/by-id using LUN ID
2. Get multipath name from multipath -ll using device names
3. Get vg and lv names from "vgdisplay -v" using multipath name
4. Make sure that device is not mounted ( mount | grep <device>), otherwise umount
5. No open files (not possible after umount but just in cases), lsof | grep <device>
6. Device is not listed in activated volumegroups (vgdisplay -v), else deactivate using "vgchange -a n <volgroup-name>"
7. Once not listed in volumegroups remove multipath device using (multipath -f /dev/mapper/mpath<dev>
8. Now remove using "echo 1 > /sys/block/<device-name>/device/delete" for each device-name such as sda, sdb which need to be removed
9. If everything is fine following commands should finish within 1-2 seconds without any error display
   • fdisk -l
   • multipath -ll
   • vgscan
   • vgdisplay -v
   • pvscan
   • lvmdiskscan