Change SAN switch

[mogiro]

Hi,
Curretnly we have a rp8420 with 11v1 connected to a EMC DMX3 storage throw two SAN switches. We have 4 PVlinks for each disk, this is the way the connections are done:
switch 1: 2 connection from the rp8420 and two from the DMX.
switch 2: the same.
So, we are planning to change these old switches, but for security reasons we want to change them 1 by 1. This is the way I have planned to do so:
1. vgreduce the PVlinks comming from switch 1
2. unconnect switch1.
3. connect new swtich 1.
4. new zoning
5. vgscan -p -v will show me the new PVlinks paths (here is my doubt).
6. vgextend the new PVlinks.

So, my doubt is: will vgscan show me only which disks belong to the same VG but it will be not able to know which VG?
IS this way the most efficient or does anybody know another way to do so?

Thanks in advance!!

[stephen peng]

maybe you should use vgscan -a -p -v, but I never try to operate like this. when changing a switch, I consider the specific LUN's device files on os get same t*d* suffix, it is more clearer for me to vgextend the new PVlinks having the same t*d*(make a chart to show the storage layout before). remember to insf after you swap the switch.

[mogiro]

Ok, great!!
It was another of my doubts. If I'm only change the SAN switch, not the FC card on the machine neither the EMC storage, the only number on the device file that is going to change is the first one? If it is true, then the easiest way of do the change is as yu have said, vgextend the same txdy.
But are u absolutely sure that only this number is going to change? I have allways doubts about how the device file name is created...
Thanks!!

[stephen peng]

as I recall, it only changed c* of the device file if I only swap switch(I use the same port as before for a specific fibre),of course this is based on my experience. anyway, this process is reversable, right? so, it is quite important to note the layout of storage before such maintenance.

regards

[Kevin Wright · Accepted solution]

make sure you have map files of the VG's with vgexport -p -s ...

Keep the domain ID of the switch the same, and ensure the same switchports are used, and the HW paths should remain the same.. otherwise, yes, you'll need to ioscan/insf and vgextend to the new paths, or a complete vgexport/vgimport.

[stephen peng]

agree to Kevin, you don't need to vgreduce and vgextend if you follow Kevin's hint-reuse the domain id and ensure the same switch port.

[mogiro]

Hi all again,
Just to close the thread. LAst weekend we performed the SAN switches change and, as you said, only the cxx number from the cxxtxxdxx disk name changed, so we issued vgreduce and vgextend to remove the old path to the disk and include the new one.
Thanks!!

[mogiro]

only the first cxx number from the cxxtxxdxx disk name changes