On Tue, Aug 09, 2016 at 03:50:47PM +0100, Wei Lin wrote: > Hi there, > > I am working on an xfs based project and want to modify the allocation > algorithm, which is quite involved. I am wondering if anyone could help > with this. > > The high level goal is to create xfs agains multiple physical volumes, > allow user to specify the target PV for files, and migrate files > automatically. So, essentially tiered storage with automatic migration. Can you describe the storage layout and setup you are thinking of using and how that will map to a single XFS filesystem so we have a better idea of what you are thinking of? > I plan to implement the user interface with extended attributes, but am > now stuck with the allocation/migration part. Is there a way to make xfs > respect the attribute, i.e. only allocate blocks/extents from the target > PV specified by user? Define "PV". XFS separates allocation by allocation group - it has no concept of underlying physical device layout. If I understand what you , you have multiple "physical volumes" set up in a single block device (somehow - please describe!) and now you want to control how data is allocated to those underlying volumes, right? So what you're asking about is how to define and implement user controlled allocation policies, right? Sorta like this old prototype I was working on years ago? http://oss.sgi.com/archives/xfs/2009-02/msg00250.html And some more info from a later discussion: http://oss.sgi.com/archives/xfs/2013-01/msg00611.html And maybe in conjunction with this, which added groupings of AGs together to form independent regions of "physical separation" that the allocator could then be made aware of: http://oss.sgi.com/archives/xfs/2009-02/msg00253.html These were more aimed at defining failure domains for error and corruption isolation: http://xfs.org/index.php/Reliable_Detection_and_Repair_of_Metadata_Corruption#Failure_Domains Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
