what's pvlink

[watermelonyu]

最近聽到pvlink這個東西

請問他是做什麼的,我要怎樣使用它???

[watermelonyu]

也稱備援介面，可以防止 I/O 通道的單點失效, 簡單來說, 在LVM架構下pv_link提供所謂的redundant path,或稱

alternative link, 其他相同的產品如Veritas DMP, EMC powerpath

[watermelonyu]

那怎樣管理呢?

是要將同一個lun 同時指定到一個vg嗎???

EMC powerpath可以看到下列的東西，pvlink可以這樣做嗎

不然我怎樣知道哪些disk同一個呢?

# powermt display dev=all

CLARiiON ID=CK200030505413

Logical device ID=60060160AF801000FB786F6D34BFD811

state=alive; policy=CLAROpt; priority=0; queued-IOs=0

Owner: default=SP A, current=SP A

==============================================================================

---------------- Host --------------- - Stor - -- I/O Path - -- Stats ---

### HW Path I/O Paths Interf. Mode State Q-IOs Errors

==============================================================================

12 1/0/10/0/1.3.0.0.0.0.1 c12t0d1 SP A1 active alive 0 1

14 1/0/10/0/1.3.32.0.0.0.1 c14t0d1 SP B2 active alive 0 1

29 1/0/8/0/0.1.16.0.0.0.1 c29t0d1 SP A2 active alive 0 0

31 1/0/8/0/0.1.48.0.0.0.1 c31t0d1 SP B1 active alive 0 0

[watermelonyu]

可藉由兩種方式來判斷, 不同的pv link是否指向同一顆pv

1. 根據cable的接法.

2. 使用附檔的工具



save attach script as cmpdisks

chmod 700 cmpdisks

./cmpdisks

----------- sample --------- result ------------

testenv:c1t0d5 1279364181-1052896481 8/4.0.5 HP/C5447A (0x05/vg_xyz/1279364181-1052896494)

testenv:c8t1d5 1279364181-1052896481 12/12.1.5 HP/C5447A (0x05/vg_xyz/1279364181-1052896494)

----------- sample --------- result ------------

[watermelonyu]

如果你有pv_link, 那麼在下vgdisplay 時, 會多出現一行

PV Name /dev/dsk/cXtXdX Alternate Link

[watermelonyu]

Yes, Matthew is correct. But as I know, pv_link does not like Veritas's DMP (Dynamic MultiPath) which allow more than 1 active path work at the same time. pv_link only work 1 path, the other path will only be active when the first path is failed.

PS. I'm not sure if new version's pv_link has the ability like Veritas DMP.