Bug 157357

Summary: Limited number of loopbackdevices
Product: [openSUSE] SUSE Linux 10.1 Reporter: Hans Witvliet <hwit>
Component: XenAssignee: Olaf Dabrunz <odabrunz>
Status: RESOLVED DUPLICATE QA Contact: E-mail List <qa-bugs>
Severity: Minor    
Priority: P5 - None CC: suse-beta
Version: Beta 6   
Target Milestone: ---   
Hardware: x86   
OS: SuSE Linux 10.1   
Whiteboard:
Found By: Beta-Customer Services Priority:
Business Priority: Blocker: ---
Marketing QA Status: --- IT Deployment: ---

Description Hans Witvliet 2006-03-10 23:59:43 UTC 
Firstly let me state that the "problem" exist for elder releases probaly as well.

For xen you can define partitions for DOMu in two ways: either as a file or as a raw partition. For several reasons i choosed to use a file.
Traditionally i split major file systems in seperate partitions for "normal" unix installations. So I did this also with XEN.

I noticed that for each file-image that is fed to the DOMu, a loopback device is used. If one uses eight partitions for a DOMu, all is fine. But beyond that DOMu wont start and even worse is does not give a clue why not.

After some expermenting i found that the number of loopback devices is by default set to eight. Which implies that one can create either one DOMu with 8 partitions, or eight domains with one partition.
Or increase the number of loopback devices.

As it is nolonger a module, on has to set it as a kernel parameter in the grub-config (max_loop=256) and create the devices in /dev.

Specially when using a XEN-kernel, it would be nice if the number of loopback devices were already increased to 256.

As XEN is going to be included into sles-10, it would be a nice enhancement, small as it is. Specially as XEN does not come with a clear error (neither from xm, neither in /var/log/xend.log)

Hans
Comment 1 Michael Gross 2006-03-13 12:23:09 UTC 
Should be done by the YaST bootloader module. The number of loop device nodes were lowered since 9.3.
Comment 2 Jan Beulich 2006-03-15 10:59:13 UTC 
No, in 10.1/SLES10 the loopback driver is a module, hence the boot loader has no control.
Comment 3 Hans Witvliet 2006-03-21 09:32:13 UTC 
OK, 
(is it a module or built-in for sles10)??
but can the default number be raised? (preferably)
Adding in /etc/modprobe.conf the line: "loop max_loop=256"
or in anyway, having it documented in the XEN-chapter.
Comment 4 Glen Davis 2006-04-07 21:01:10 UTC 
I am also seeing the problem using Xen.  Any idea on what Beta we may see a fix in?
Comment 5 Christian Boltz 2006-04-07 23:55:08 UTC 
Please have a look at bug 141950, comment #7.

*** This bug has been marked as a duplicate of 141950 ***