Commit 6c297d03 authored by Russ Fish's avatar Russ Fish
Browse files

More about the 30-mount-point Cygwin limitation, and circumventing it using Emulab subgroups.

parent d82956ba
......@@ -744,9 +744,10 @@ another alias for Ops/Users, via the SMB protocol (Server Message Block, also
known as Windows File Sharing) with the Windows Client connecting to the Samba
server. <p>
UNC paths with leading double-slashes <b><code>//fs</code></b> are used to
access the SMB Shares under Cygwin. They are then further mounted to the
usual Unix paths for the shared directories:
UNC paths with leading double-slashes and a server name,
e.g. <b><code>//fs</code></b>, are used to access the SMB Shares under Cygwin.
Emulab then uses the <a href="#Cygwin_mounts"> Cygwin mount command </a> to
make them appear on the usual Unix paths for the Emulab shared directories:
<code>/users/&lt;username&gt;</code>, <code>/proj/&lt;pid&gt;</code>,
<code>/group/&lt;pid&gt;/&lt;gid&gt;</code>, and <code>/share</code>.
<p>
......@@ -765,16 +766,22 @@ or a file-open dialog with <b>backslashes</b>, e.g. <code>\\fs\share</code> or
<code>\\fs\&lt;username&gt;</code>. User and project shares are marked "not
browsable", so just <code>\\fs</code> shows only <code>share</code>. <p>
Windows limitation: There is only one protection mask for everything in a
whole mount/share under SMB. It's set in the "share properties" on the server
(Samba config file in this case) so <b><code>chmod</code></b> will do you no
good across SMB.
<i>Windows limitation:</i> There is only <b>one protection mask</b> for
everything in a whole mount/share under SMB. It's set in the "share
properties" on the server (Samba config file in this case) so
<b><code>chmod</code></b> will do you no good across SMB. <p>
<i>Cygwin limitation:</i> There is a hard-coded <b>limit of 30 mount
points</b> in Cygwin. Cygwin uses 4 of them, and Emulab uses another 3 or 4.
So some of your <code>/users</code> mounts will fail on Windows startup if you
have more than 23 or 24 members in your project, unless they are grouped into
smaller <a href="../docwrapper.php3?docname=groups.html"> subgroups </a>.
<h4><a name="Cygwin_arcana"> </a> Cygwin arcana </h4>
<ul>
<li> Paths <p>
<li> <a name="Cygwin_paths"> </a> Paths <p>
Cygwin accepts either flavor of slashes in paths, Unix/POSIX-style
forward-slashes, or Windows-style back-slashes. In Unix shell
......@@ -788,14 +795,16 @@ good across SMB.
are expanded in double-quotes.) <p>
When you invoke Windows (as opposed to Cygwin) commands, for example
<b><code>net use</code></b>, they will know nothing about Unix-style paths in
their arguments. The <a
<b><code>net use</code></b>, they will know nothing about Unix-style
paths in their arguments. The <a
href="http://cygwin.com/cygwin-ug-net/using-utils.html#cygpath">
<b><code>cygpath</code></b> </a> utility is an aid to converting paths
between the Unix and Windows conventions. <p>
<code>cygpath -w</code> converts its arguments to Windows format, where <code>cygpath
-u</code> converts its arguments to Unix format, e.g. <pre>
<code>cygpath -w</code> converts its arguments to Windows format, and
<code>cygpath -u</code> converts its arguments to Unix format,
e.g. <pre>
$ cygpath -w /cygdrive/c/WINDOWS
c:\WINDOWS
......@@ -803,7 +812,7 @@ good across SMB.
/cygdrive/c/WINDOWS
</pre> <p> </li>
<li> Cygwin mounts <p>
<li> <a name="Cygwin_mounts"> </a> Cygwin mounts <p>
<a href="http://cygwin.com/cygwin-ug-net/using-utils.html#mount">
Cygwin mount points </a> are shown by the <b><code>mount</code></b> and
......@@ -813,13 +822,13 @@ good across SMB.
Attempts to use the Cygwin <code>mount</code> command after that will
fail. <p>
We discussed UNC <code>//machine</code> paths to SMB shares <a
href="#SMB_mounts"> above </a>. <p>
See the discussion of mount points and UNC <code>//machine</code>
paths to SMB shares <a href="#SMB_mounts"> above </a>. <p>
Another special case is the <b>Unix root</b>, "<code>/</code>". It's
mounted to <code>C:\cygwin</code> in the Windows filesystem. </li>
<li> Windows drive letter mounts <p>
<li> <a name="Cygwin_drive_letters"> </a> Windows drive letter mounts <p>
Cygwin knows about drive letter prefixes like
<b><code>C:</code></b>&nbsp;, which are equivalent to
......
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