EVA Disk Device Changes

[Cliff Lim Kok Hwee]

Hi Forumers,

I will be having my existing 8 port SAN switch (non-HP) to be changed to a 8 port SAN switch (HP).

All SAN connectivities will be left unchanged.

Query:

- Will the disks device file changed upon the new SAN switch changed?
- If so I will be doing the following
1)vgexport -p -v -s -
and safe the mapfile.
2)vgexport the existing vg
3)mkdir /dev/vgname
chmod 755 /dev/vgname
mknod /dev/vgname/group c 64 0x010000
4)vgimport -v -s

I encounter before the vgexport of -s option will automatically take care of the device file should there be changes.

Any advises on my steps and findings?

Thanks/Cliff

[Chan 007]

Hi Cliff,

Theoritically it should not change you dev files.

Only thing you missed out is "ioscan -fCdisk" and "insg -e"
#1 missed the -m
#4 does not have the /dev/dsk/
#5 vgchange -a y

Also what ever you have said is sufficient in the event of a change in dev file.

My advice is don't do all servers in one go. Just do one by one.

Please ensure you shutdown the application. Connect to the new san port.

All the best.

Chan

[Albert_31]

Hello Cliff,

Yes, you are right the device files may change so it is better to be on the safer side..wanted to add some changes to ur action plan..

Before the SAN changes
# vgexport -p -v -s -m
# vgcfgbackup /dev/vgname
# cp -p /etc/lvmtab /etc/lvmtab.
# cp -p /etc/lvmconf/vgnaem.conf /etc/lvmconf/vgname.date
# list of PV's part of this vg..

Once the changes on the san are completed..

# ioscan -fn
# insf -e (to recreate the device files)
# check if the device files have changed..then
# vgexport the existing vg
3)mkdir /dev/vgname
chmod 755 /dev/vgname
mknod /dev/vgname/group c 64 0x010000
4)vgimport -p -v -s -m
If there are no errors reported above then proceed further,else resolve the errors before proceeding..

# vgimport -v -s -m
# vgcfgbackup /dev/vgname

Hope this helps..

regards

albert

[BPatrick]

Any changes to the fabric will result in the change of device files. Son in your case it definitely change. The steps that you metntioned are correct.

[Cliff Lim Kok Hwee]

Hi Guys,

As queried, I encounter before the vgexport of -s option will automatically take care of the device file should there be changes. Is that right to say?

Thanks/cliff

[BPatrick]

vgexport and then vgimport are the safest way to make sure that you will have the same device name even after the changing your SAN switch.
If the device file name change is not a problem then, after the changing switch you can do a vgscan to re-create the lvmtab file with the new device names.
you can use vgscan -a -v
and then vgchange -a -y to resync the information on the disk