Well, the tricky thing is that the varstrip configuration parameters
actually reference each strip by a data object index (i.e. the 0th, 1st,
2nd... datafile) relative to that particular file. Each file in turn
will have a different permutation of which datafile maps to which server
for load balancing reasons. So the 0th strip on one file might point to
hostA and the 0th strip on another file might point to hostB.
As a result, the varstrip distribution by itself still won't let you
restrict a file to a specific set of servers. You would still need a
layout.
In general, the breakdown of responsibility is that the layout controls
the selection of servers, but then the distribution controls the
organization of data within that set.
-Phil
On 06/03/2015 12:20 PM, Dorier, Matthieu wrote:
Or can I use a varstrip_dist distribution on a directory and set the strip
sizes to 0 for servers I don't want to use?
Matthieu
________________________________________
From: Dorier, Matthieu
Sent: Wednesday, June 03, 2015 11:18 AM
To: Phil Carns; [email protected]
Subject: RE: [Pvfs2-users] Changing distribution/layout using PVFS API
Good to know. So there is no way to associate a particular directory to a
particular set of servers, correct?
Matthieu
________________________________________
From: [email protected]
[[email protected]] on behalf of Phil Carns
[[email protected]]
Sent: Wednesday, June 03, 2015 11:06 AM
To: [email protected]
Subject: Re: [Pvfs2-users] Changing distribution/layout using PVFS API
Just a heads up on something to look out for: if I recall correctly you
can set the distribution and its parameters on a directory (and it will
then apply to newly created files in that directory), but the same might
not be true of layouts. You might have to specify the layouts
explicitly at create time rather than inheriting them from directory hints.
-Phil
On 06/03/2015 11:56 AM, Dorier, Matthieu wrote:
It does help, thanks!
Matthieu
________________________________________
From: Elaine Quarles [[email protected]]
Sent: Wednesday, June 03, 2015 10:36 AM
To: Dorier, Matthieu
Cc: [email protected]
Subject: Re: [Pvfs2-users] Changing distribution/layout using PVFS API
Matthieu,
You can look in the source tree at src/apps/admin/pvfs2-xattr.c for an
example of using the PVFS_sys_seteattr function call to set
attributes.
Hope that helps!
Elaine
On Wed, Jun 3, 2015 at 10:56 AM, Dorier, Matthieu <[email protected]> wrote:
Hi,
I'm reading this page:
http://www.orangefs.org/trac/orangefs/wiki/Distributions
Could you give me an example of how to change the layout of an existing
directory using PVFS_SYS_LAYOUT_LIST and the PVFS API (instead of setfattr)?
Thanks,
Matthieu
________________________________
Matthieu Dorier, PhD
Postdoctoral Appointee
Argonne National Laboratory, MCS
9700 S Cass Ave, Lemont, IL 60439
+1 630 252 1515
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