Exposing disk with multiple paths?

[zeha]

I would like to test dm-multipath setups inside VMs. Is there a way to expose a scsiN device as multiple paths/devices?

Unsupported hacks would be good enough, obviously

Chris

 

[fabian]

IIRC using the same raw image (with cache=none) and serial for two scsi devices should work - but obviously for testing purposes only

 

[zeha]

That works, indeed:

scsi1: pve_disk_02:vm-113-disk-1,cache=none,serial=YYYYYNN,wwn=0x5001438032b17f50,size=8G scsi2: pve_disk_02:vm-113-disk-1,cache=none,serial=YYYYYNN,wwn=0x5001438032b17f50,size=8G

Plus, for VirtIO SCSI, add boot param scsi_mod.default_dev_flags=0x10000000 to force VPD read.

Thanks!

 

[LnxBil]

For testing such setups, I always use a storage VM with two IPs, exporting a LUN to another machine via SCSI and using the default iSCSI stack on the client with multiple portals to have "real" multipath over iSCSI. Another way I usually go is with a fiberchannel-SAN, I passthrough a dual port card and have proper SAN integration.

 

[zeha]

Right. I do have such an iSCSI setup, but if I don’t have to use it, it’s better for me. (And FC can die in a lonely corner for all I care …)