<HTML>
<HEAD>
<TITLE>Summary of our HSM discussion</TITLE>
</HEAD>
<BODY>
<FONT FACE="Calibri, Verdana, Helvetica, Arial"><SPAN STYLE='font-size:11pt'>We spoke about the HSM plans some 10 days ago. I think that the conclusions are roughly as follows:<BR>
<BR>
</SPAN></FONT><OL><LI><FONT FACE="Calibri, Verdana, Helvetica, Arial"><SPAN STYLE='font-size:11pt'>It is desirable to reach a first implementation as soon as possible.
</SPAN></FONT><LI><FONT FACE="Calibri, Verdana, Helvetica, Arial"><SPAN STYLE='font-size:11pt'>Some design puzzles remain to insure that HSM can keep up with Lutre metadata clusters<BR>
</SPAN></FONT></OL><FONT FACE="Calibri, Verdana, Helvetica, Arial"><SPAN STYLE='font-size:11pt'><BR>
The steps to reach a first implementation can be summarized as:<BR>
<BR>
</SPAN></FONT><OL><LI><FONT FACE="Calibri, Verdana, Helvetica, Arial"><SPAN STYLE='font-size:11pt'>Include file closes in the changelog, if the file was opened for write. Include timestamps in the changelog entries. This allows the changelog processor to see files that have become inactive and pass them on for archiving.
</SPAN></FONT><LI><FONT FACE="Calibri, Verdana, Helvetica, Arial"><SPAN STYLE='font-size:11pt'>Build an open call that blocks for file retrieval and adapts timeouts to avoid error returns.
</SPAN></FONT><LI><FONT FACE="Calibri, Verdana, Helvetica, Arial"><SPAN STYLE='font-size:11pt'>Until a least-recently-used log is built, use the e2scan utility to generate lists of candidates for purging.
</SPAN></FONT><LI><FONT FACE="Calibri, Verdana, Helvetica, Arial"><SPAN STYLE='font-size:11pt'>Translate events and scan results into a form that they can be understood by ADM.
</SPAN></FONT><LI><FONT FACE="Calibri, Verdana, Helvetica, Arial"><SPAN STYLE='font-size:11pt'>Work with a single coordinator, whose role it is to avoid getting multiple “close” records for the same file (a basic filter for events).
</SPAN></FONT><LI><FONT FACE="Calibri, Verdana, Helvetica, Arial"><SPAN STYLE='font-size:11pt'>Do not use initiators – these can come later and assist with load balancing and free-ing space on demand (both of which we can ignore for the first release)
</SPAN></FONT><LI><FONT FACE="Calibri, Verdana, Helvetica, Arial"><SPAN STYLE='font-size:11pt'>Do not use multiple agents – the agents can move stripes of files etc, and this is not needed with a basic user level solution, based on consuming the log. The only thing the agent must do in release one is get the attention of a data mover to restore files on demand.<BR>
</SPAN></FONT></OL><FONT FACE="Calibri, Verdana, Helvetica, Arial"><SPAN STYLE='font-size:11pt'><BR>
Peter<BR>
</SPAN></FONT>
</BODY>
</HTML>