[Linux-HA] Q: limiting parallel execution of resource actions

[Ulrich Windl]

Hi!

I have a wuestion: If I want to limit parallel execution of some resources, how 
can I configure that?

Background: Some resources may hit some OS bug when demanding high I/O (e.g. 
starting several Xen-VMs residing on a OCFS2 filesystem that is mirrored by 
cLVM). The I/O performance will drop approximately to zero when cLVM is also 
mirroring. That's not because of the I/O channel being saturated, but because 
of terrible programming regarding cLVM... anyway:

Would it work to define an advisory ordering of resources (in addition to a 
different mandatory ordering), so if crm would schedule alle those resources at 
one (in parallel), it would actually schedule the sequentially?

If I stop one resource, will those logically after the one being stopped be 
also stopped due to advisory ordering then?

Maybe a new mechanism is needed to restrict parallelism based on resources 
(i.e. a new type of constraint).

Regards,
Ulrich


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Re: [Linux-HA] Q: limiting parallel execution of resource actions

[David Vossel]

- Original Message -
 From: Ulrich Windl ulrich.wi...@rz.uni-regensburg.de
 To: linux-ha@lists.linux-ha.org
 Sent: Monday, April 15, 2013 1:39:34 AM
 Subject: [Linux-HA] Q: limiting parallel execution of resource actions
 
 Hi!
 
 I have a wuestion: If I want to limit parallel execution of some resources,
 how can I configure that?
 
 Background: Some resources may hit some OS bug when demanding high I/O (e.g.
 starting several Xen-VMs residing on a OCFS2 filesystem that is mirrored by
 cLVM). The I/O performance will drop approximately to zero when cLVM is also
 mirroring. That's not because of the I/O channel being saturated, but
 because of terrible programming regarding cLVM... anyway:
 
 Would it work to define an advisory ordering of resources (in addition to a
 different mandatory ordering), so if crm would schedule alle those resources
 at one (in parallel), it would actually schedule the sequentially?
 
 If I stop one resource, will those logically after the one being stopped be
 also stopped due to advisory ordering then?
 
 Maybe a new mechanism is needed to restrict parallelism based on resources
 (i.e. a new type of constraint).

hey,

'batch-limit' cluster option might help.

http://clusterlabs.org/doc/en-US/Pacemaker/1.1-pcs/html-single/Pacemaker_Explained/index.html#_available_cluster_options

-- Vossel

 Regards,
 Ulrich
 
 
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