topic Re: FC60 and volume groups in Disk Enclosures

FC60 and volume groups

Jan den Rooijen — Sat, 03 Feb 2001 18:11:47 GMT

We have ordered a FC60 with 6 sc10's, each with 4 18Gb-disks.
According to a note in the FC60 Advanced User Guide, LVM will override the ownership.

For example (all from the manual, FC60 is not installed yet):
Create 2 RAID 0/1 LUN's:
amcfg -L A:0 -d 1:0,2:0,3:0,4:0,5:0,6:0 -r 10 -S
amcfg -L B:1 -d 1:8,2:8,3:8,4:8,5:8,6:8 -r 10 -S
Ioscan will show 4 device files:
/dev/dsk/c4t0d0 (LUN0, controller A)
/dev/dsk/c4t0d1 (LUN1, controller A)
/dev/dsk/c5t0d0 (LUN0, controller B)
/dev/dsk/c5t0d1 (LUN1, controller B)

Q1) How to create volume groups with LVM:
A) use primary path (what happens if controller A fails, will vg04 automatically change to controller B?):
vgcreate /dev/vg04 /dev/dsk/c4t0d0
vgcreate /dev/vg05 /dev/dsk/c5t0d1
B) both primary and alternate paths (is this necessary in case of a controller failure?):
vgcreate /dev/vg04 /dev/dsk/c4t0d0 /dev/dsk/c5t0d0
vgcreate /dev/vg05 /dev/dsk/c5t0d1 /dev/dsk/c4t0d1

Q2) Can you change the ownership for LUN1 afterwards (or will LVM still overrule this?):
vgcreate /dev/vg04 /dev/dsk/c4t0d0
vgcreate /dev/vg05 /dev/dsk/c4t0d1
amcfg -M 1 -C B

Regards

Re: FC60 and volume groups

Insu Kim — Mon, 05 Feb 2001 00:19:11 GMT

For Q1) answer is B
For Q2,
Yes, You can change the ownership of a bound LUN without unbining and binding LUN again.
This can be done if you'd like to share load between controllers.

Best regards,

Re: FC60 and volume groups

Alexander M. Ermes — Mon, 05 Feb 2001 15:26:37 GMT

Hi there.
Answer B is the way to go.
In case of a failure access goes through controler B, second you can share the load between the two controlers.
If you need mire info about this, just contact me ( ger7axe@europe.ups.com ).
Rgds
Alexander M. Ermes