[Lustre-devel] Lustre HSM HLD draft

Canon, Richard Shane canonrs at ornl.gov
Mon Feb 18 13:51:35 PST 2008

Aurelien and JC,

Sorry that my feedback is late.  Here are my questions/remarks.

* Any thought on how quotas will be handled?

* 3.4 - I was curious what the precise use case was that was driving
this?  I don't disagree with it, but I was curious for more background
* 3.7.1 - The coordinator could become a scaling bottleneck.  We should
think about how this will be scaled in the future
* 4.1 - Does the coordinator store the ext obj id or does the agent
* 4.3 item 2 - This looks like the coordinator could become a bottle
neck for unlinks and slow down performance.  Could this be put in some
type of async queue to be processed later (or some type of attic space)?

Use Cases
* 2.3 (Use cases) - I'm really keen on this feature.  I think it is very
important in order to make small file performance work well.
Unfortunately, it isn't clear how the file list gets communicated to the
archive tool.  The coordinator and agent seem to only take one file at a
time.  So how would this work exactly?
* 2.4 - The copy tool should be allowed to preemptively restage files.
I think this will work with the design, but we should make sure of this.
This would be useful for restaging a whole tar file versus doing things

Part IV
2 EAs - I'm worried that the EA list could get huge for holes.
3.2 -item 3 - Who insures a file is archived before punches are made?
3.3 - Another use case...  The user checks to see if a file has been

Also, someone earlier made the point about the archive tool being able
to reorder request.  This is really important since an archival system
wants to know all the files being restaged in order to order tape mounts
and reads.  

Thanks for taking the lead on this.  It looks like there is a lot of
interest in it.


-----Original Message-----
From: lustre-devel-bounces at lists.lustre.org
[mailto:lustre-devel-bounces at lists.lustre.org] On Behalf Of DEGREMONT
Sent: Thursday, February 07, 2008 5:53 AM
To: lustre-devel at lists.lustre.org
Subject: [Lustre-devel] Lustre HSM HLD draft


Here is a first draft for comments of the Lustre HSM HLD.
It is intended to be a support for further analyzes and comments from

The document covers the main parts of the HSM features but some elements
are still lacking.
The policy management and the space manager will be describe later.

Let us know your comments and ideas about it.


Aurelien Degremont

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