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Split BCV’s


Based on the Timfinder BCV’s you split for backup or any other purposes, here is the info you need to figure how how to mount them or use them within your symm.

The issue revolves around the volume or disk group header information. Conceptually, this is the same for both Veritas Volume manager and HP’s Logical Volume Manager. Both volume managers store information about the volume/disk group on the disks that comprise the group. So, when you split off the BCVs, the information encoded is the exact same as the information on the standard devices. There won’t be a separate volume/disk group, LV/volume to mount because everything thinks its the same thing.

So, you have to figure a way around that. Fortunately, there’s a way for both HP’s Logical volume manager and Veritas’ Volume manager.

HP Logical volume manager – vgchgid

1. Split the BCV’s from the Symmetrix disk group. Example
1. /dev/dsk/c2t0d0
2. /dev/dsk/c2t1d0
3. /dev/dsk/c3t0d0
4. /dev/dsk/c3t1d0

2. Create an array with the appropriate disk names. Creating an array is optional.

set -A bcvs /dev/dsk/c2t0d0 /dev/dsk/c2t1d0 /dev/dsk/c3t0d0 /dev/dsk/c3t1d0

3. Create an vgexport map file for the volume group – particularly if you’re using nonstandard logical volume names.

vgexport -p -m /tmp/${vg}.map

4. Create the new volume group directory structure as needed:

mkdir /dev/vgbcv
mknod /dev/vgbcv/group c 64 0x0#0000

5. Change the volume group header information on all the BCV disks simultaneously:

/usr/sbin/vgchgid ${bcvs[*]}

6. Import the new volume group

vgimport -m /tmp/${vg}.map vgbcv ${bcvs[*]}

7. Mount the filesystems and do with them as you will.

Steps to import the clone disk (including EMC BCVs) using VxVM 5.0 :

1) before we split the BCV device from vm240dg (as in example below), “vxdisk list” shows the clone disk in an error udid_mismatch status

DEVICE TYPE DISK GROUP STATUS
EMC0_1 auto:cdsdisk EMC0_1 vm240dg online
EMC0_27 auto – – error udid_mismatch

2) then issue the following command to split the BCV device

/usr/symcli/bin/symmir -g vm240dg split DEV001

3) after we split the BCV device DEV001 from vm240dg, we need to issue “vxdctl enable” or “vxdisk scandisks” to update the configuration in order to see the clone disk is in “online udid_mismatch” state issuing “vxdctl enable” ( or “vxdisk scandisks”), and “vxdisk list” gives the following display

DEVICE TYPE DISK GROUP STATUS
EMC0_1 auto:cdsdisk EMC0_1 vm240dg online
EMC0_27 auto:cdsdisk – – online udid_mismatch

4) use the following comand to import the clone disk

vxdg -n newdg -o useclonedev=on -o updateid import vm240dg

5) issue “vxdisk list” to see the clone disk is imported

DEVICE TYPE DISK GROUP STATUS
EMC0_1 auto:cdsdisk EMC0_1 vm240dg online
EMC0_27 auto:cdsdisk EMC0_1 newdg online clone_disk