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Configure iSCSI multipath in OVM 3.1.1 with storage plug-in not possible ?

pdbrmontSep 26 2012 — edited Sep 27 2012
I have a configuration with 4 iSCSI paths to storage system. All is working fine if the discover and login
process was performed manual. Multipath is working well with 4 paths.

# iscsiadm -m session
tcp: [13] 192.168.10.1:3260,25 iqn.2000-09.com.fujitsu:storage-system.eternus-dx400:CM0CA3P0
tcp: [14] 192.168.20.1:3260,26 iqn.2000-09.com.fujitsu:storage-system.eternus-dx400:CM0CA3P1
tcp: [15] 192.168.10.2:3260,27 iqn.2000-09.com.fujitsu:storage-system.eternus-dx400:CM1CA3P0
tcp: [16] 192.168.20.2:3260,28 iqn.2000-09.com.fujitsu:storage-system.eternus-dx400:CM1CA3P1

# multipath -ll
3600000e00d10000000100000000c0000 dm-2 FUJITSU,ETERNUS_DX400
size=30G features='1 queue_if_no_path' hwhandler='0' wp=rw
|-+- policy='round-robin 0' prio=50 status=enabled
| |- 25:0:0:1 sdg 8:96 active ready running
| `- 26:0:0:1 sdi 8:128 active ready running
`-+- policy='round-robin 0' prio=10 status=enabled
|- 27:0:0:1 sdk 8:160 active ready running
`- 28:0:0:1 sdm 8:192 active ready running


I want to configure iSCSI multipath in OVM manager using specific storage plug-in.
I proceed “Discover SAN Server” with following parameter:
Name: Storage-Name
Storage Type: iSCSI Storage Server
Storage Plug-in: Fujitsu ETERNUS
Admin Host: IP-Addr. of storage system
Admin Username: user name to access storage system
Admin Password: password
Access Host (IP) Address: 192.168.10.1

After this configuration I see my storage system and assigned physical volumes to an access group.
Now the volumes are available on the OVM storage server, >>>> but I lost the multipath functionality <<<<<.

# multipath -ll
3600000e00d1000000010000000120000 dm-1 FUJITSU,ETERNUS_DX400
size=30G features='1 queue_if_no_path' hwhandler='0' wp=rw
`-+- policy='round-robin 0' prio=50 status=active
`- 33:0:0:1 sdd 8:48 active ready running

The reason for this behavior is that only one Access Host (IP) Address can be specified.
With this IP address a session was established … but only 1 session and not 4 !!
How can I specify the remaining 3 paths to have proper multipath functionality?
I know that Citrix XenServer accepts more Access Host (IP) Addresses,
e.g. 192.168.10.1,192.168.10.2,192.168.20.1,192.168.20.2

Thanks for help.

Comments

user12273962
The way I understand the storage plugins... this is only for management of the storage from within the VM Manager. I don't see how this could be keeping your VM servers from being multi-pathed. Maybe I misunderstood your question.
budachst
Seems like OVM manager only logs in once to the target, otherwise multipath would surely pick up all the paths to the target. Check iscsiadm for the number of sessions as you did before. I am using iSCSI on my VM servers as well, but I don't rely on product-specific plugins, since my iSCSI storage is served from a Linux box running iscsi-target, and I am managing that manually.
pdbrmont
@user12273962
Yes, you are right. The storage plug-in is for management of the storage within OVM.
This is working well, but I'm still missing the multipath fuctionality. This storage plug-in is not responisble
for establish the multipath, but OVM should take care of this.

@budachst
Yes, OVM did only open one session and loggin only to one target, because only one Access Host (IP) Address: 192.168.10.1
can be specified.
# iscsiadm -m session
tcp: [21] 192.168.10.1:3260,25 iqn.2000-09.com.fujitsu:storage-system.eternus-dx400:CM0CA3P0

In my point of view it is not possible to configure the remaining targets, so this is a design problem.

Any new inputs and informations are welcome.
budachst
Since OVM wont't give you multipathing right away, your only choice seems to configure your iSCSI targets yourself (like I did for my Linux boxes) and enjoy multipathing this way on your VM servers. Not the most convenient way to handle this and certainly a lack on OVMM, but it works nevertheless.
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Locked on Oct 25 2012
Added on Sep 26 2012
#oracle-virtualization, #oracle-vm-server-for-x86
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