<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<meta content="text/html; charset=ISO-8859-15"
http-equiv="Content-Type">
</head>
<body bgcolor="#ffffff" text="#000000">
<font face="Times New Roman">Dear all,<br>
<br>
Concerning:<br>
</font><br>
On 9/24/11 4:35 AM, Estanislao Gonzalez wrote:
<blockquote cite="mid:4E7DC078.5000700@dkrz.de" type="cite">
<pre wrap="">2) checksums
They are the only reference to the outside that a data node give of the
changes a file suffered from one version to another, i.e. for
replication we use that information to retrieve only files that change
from one version to another. The same principle could be applied for
tools designed for end users.
</pre>
</blockquote>
<br>
without disputing that checksums should be mandatory, I want to
point out that a user who has lost the checksum associated with a
file he has downloaded shouldn't have to recompute the checksum to
determine whether his file is a copy of a file residing at the
datanode. Recall that recorded in each netCDF file is a unique
tracking_id, which I'm almost positive is also in the thredds
catalog. It will certainly be quicker for the user to read the
tracking_id and then check whether it matches the latest version. I
think we want to maintain tracking_id as an option for checking
whether new files exist in a new version.<br>
<br>
best regards,<br>
Karl<br>
</body>
</html>