Author: ultrotter
Date: 2006-04-05 09:27:25 +0000 (Wed, 05 Apr 2006)
New Revision: 150
Modified:
trunk/xen-3.0/debian/xen-utils-3.0.README.Debian
Log:
Add a couple of notices about loop devices
Modified: trunk/xen-3.0/debian/xen-utils-3.0.README.Debian
==================================================================---
trunk/xen-3.0/debian/xen-utils-3.0.README.Debian 2006-03-27 14:35:29 UTC (rev
149)
+++ trunk/xen-3.0/debian/xen-utils-3.0.README.Debian 2006-04-05 09:27:25 UTC
(rev 150)
@@ -65,6 +65,30 @@
possibly /etc/network/interfaces to decide how to connect your domains to
the network.
+* About loop devices:
+
+ If you plan hosting virtual domains with file backed block devices (ie. the
+ ones xen-tools creates by default) be careful about two issues:
+
+ 1. Maximum number of loop devices
+ By default the loop driver supports a maximum of 8 loop devices. Of
+ course since every xen domain uses at least two (one for the data and one
+ for the swap) this number is absolutely insufficient. You should increase
+ it by adding a file named local-loop in /etc/modprobe.d containing the
+ string "options loop max_loop=128", if the loop driver is
compiled as a
+ module, or by appending the string max_loop=128 to your kernel parameters
+ if the driver is in-kernel. Of course you can increase or decrease the
+ number 128 as you see fit.
+
+ 2. Driver loading (only if loop is compiled as a module)
+ Normally the loop driver gets loaded when the first loop device is
+ accessed. When using udev, though, the loop devices get created only
+ after the driver gets loaded. This means that xen will fail if the loop
+ driver is not already loaded when it tries to start a file-backed virtual
+ domain. To fix this just add "loop" in your /etc/modules file,
thus
+ forcing it to be loaded at boot time.
+
+
Kindly yours,
Guido Trotter, for the Debian Xen Team.