Re: [Xen-users] problem with extra storage via iscsi

[Gertjan Oude Lohuis <gertjan@xxxxxxx>]

Tammo Schuelke wrote:
> > open-iscsi assigns the discoverd LUN also to /dev/sda
> >     
> So the domU does stop working since it's losing its root partition?
> If not, what's the output of udevinfo -q symlink -n /dev/sda?
>   
Thanks for your reply!

No, the domU keeps working, I think because all partitions are already 
mounted when open-iscsi starts. Output of udevinfo:
root@guest1 ~ # udevinfo -q symlink -n /dev/sda
disk/by-id/scsi-36006048c630e7b571c1ed50a0956f129 
disk/by-path/ip-10.4.1.201:3260-iscsi-iqn.1992-05.com.emc:ck2000809002410000-7-lun-1
> In general, iSCSI from within a domU should be working since it's plain TCP/IP.
Yes, that is exactly what I thought.

> Performance wise it would probably be better to connect to the targets in dom0 
> and assign the LUN to domU as a regular block device.
>   
Why would performance be better with an extra layer (dom0)? Connecting 
the LUN to dom0 and assigning it as a regular blockdevice to domU has a 
large drawback: there is no protection against using the same 
blockdevice in multiple domU's. Normally LUN masking would protect 
against that, but a LUN mask is based on IQN, and the IQN belongs to the 
dom0.

Regards,
Gertjan Oude Lohuis

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