[Xen-users] Maximum hard drives in domU?

[Penguinz <penguinzz@xxxxxxxxx>]

Hi,

Is there a maximum number of drives that can be exported to a domU? Xen doesn't seem to be able to handle more than 39 drives in a vm.

In a Solaris 11 Express domU, the error looks like:

...

/xpvd/xdf@51754 (xdf37) online

xdf@51754: 3907029168 blocksxdf@51755, xdf38

xdf38 is /xpvd/xdf@51755

/xpvd/xdf@51755 (xdf38) online

xdf@51755: 3907029168 blocksxdf@51772, xdf39

xdf39 is /xpvd/xdf@51772

/xpvd/xdf@51772 (xdf39) online

WARNING: xvdi_init_dev: cannot add watches for device/vbd/51773

xdf@51772: 3907029168 blocksWARNING: xvdi_init_dev: cannot add watches for device/vbd/51773

WARNING: xvdi_init_dev: cannot add watches for device/vbd/51774

...

The first 39 drives come online fine, but the next 2 fail. This happens both with a solaris domU and a test gentoo domU I created.

Linux error looks like:

vbd vbd-5632: 16 xlvbd_add at /local/domain/0/backend/qdisk/5/5632

vbd vbd-5632: failed to write error node for device/vbd/5632 (16 xlvbd_add at /local/domain/0/backend/qdisk/5/5632)

vbd vbd-5632: 16 xlvbd_add at /local/domain/0/backend/qdisk/5/5632

vbd vbd-5632: failed to write error node for device/vbd/5632 (16 xlvbd_add at /local/domain/0/backend/qdisk/5/5632)

Been using Xen for years, just never tried attaching so many drives before. Didn't ever read anything about there being a maximum.

My initial configuration that I'd been using stabley for the past few months was Xen 4.1 on top of gentoo xen-sources 2.6.38. After I encountered this issue and couldn't find any solutions, I upgraded xen to the latest 4.2-unstable. Same drive limitation. Then I upgraded the kernel to a vanilla 3.0.4 and to my surprise the hypervisor actually booted first try. Had to monkey with my domU cfg a bit and change all the "phy:/dev/..." to "tap2:/dev/..." but domain booted. Same issues though.

The issue seems to be just the number of drives. Eg, if I comment out drives 30 and 31, drives 40 and 41 start working. Or if I only comment out drive 35, drive 40 starts working but 41 still does not.

Any ideas on how to increase the number of drives in a domU?

_______________________________________________
Xen-users mailing list
Xen-users@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-users