[PVFS2-CVS] commit by neill in pvfs2/doc: pvfs2-faq.tex

CVS commit program cvs at parl.clemson.edu
Tue Nov 23 15:24:26 EST 2004


Update of /projects/cvsroot/pvfs2/doc
In directory parlweb:/tmp/cvs-serv1082/doc

Modified Files:
	pvfs2-faq.tex 
Log Message:
- added an RHEL ES check as well
- added some faq entries regarding redhat


Index: pvfs2-faq.tex
===================================================================
RCS file: /projects/cvsroot/pvfs2/doc/pvfs2-faq.tex,v
diff -p -u -r1.20 -r1.21
--- pvfs2-faq.tex	29 Oct 2004 15:10:07 -0000	1.20
+++ pvfs2-faq.tex	23 Nov 2004 20:24:26 -0000	1.21
@@ -389,11 +389,11 @@ commonly the case!
 
 \subsection{PVFS2 server consumes 100\% of the CPU}
 
-On some systems, the pvfs2-server will start consuming 100\% of the CPU after
-you try to read or write a file to PVFS2.  Please check to see if your
-distribution has an updated glibc package.  RHEL3, for example, will exhibit
-this behavior with glibc-2.3.2-95.6, but not with the updated glibc-2.3.2-95.20
-package.
+On some systems, the pvfs2-server will start consuming 100\% of the
+CPU after you try to read or write a file to PVFS2.  Please check to
+see if your distribution has an updated glibc package.  RHEL3, for
+example, will exhibit this behavior with glibc-2.3.2-95.6, but not
+with the updated glibc-2.3.2-95.20 package.
 
 %
 % PERFORMANCE
@@ -487,8 +487,8 @@ particularly one with small accesses.
 \subsection{Can the underlying local file system affect PVFS2 performance?}
 
 Yes!  However, the interaction between the PVFS2 servers and the local
-file system hosting the storage space has not been fully explored.
-No doubt a great deal of time could be spent on different file systems
+file system hosting the storage space has not been fully explored.  No
+doubt a great deal of time could be spent on different file systems
 and their parameters.
 
 People have looked at sync performance for a variety of file systems.
@@ -503,8 +503,46 @@ These tests demonstrate wide variance in
 Interested users are encouraged to experiment and discuss their
 findings on the PVFS2 lists.
 
-If you're looking for a quick suggestion for a local file system type to use, we
-suggest ext3 with ``journal data writeback'' option as a reasonable choice.
+If you're looking for a quick suggestion for a local file system type
+to use, we suggest ext3 with ``journal data writeback'' option as a
+reasonable choice.
+
+\subsection{I'm running Redhat and the pvfs2-server can't be killed! What's wrong?}
+
+On some Redhat systems, for compatibility reasons, the pvfs2-server
+program is actually a script that wraps the installed pvfs2-server
+binary.  We do this ONLY if we detect that PVFS2 is being installed on
+a system with an NPTL implementation that we're incompatible with.
+Specifically, the script exports the LD_ASSUME_KERNEL=2.2.5
+environment variable and value to avoid using the NPTL at run-time.
+The script quite literally exports this variable and then runs the
+installed pvfs2-server binary which is named
+\texttt{pvfs2-server.bin}.  So to properly shutdown or kill the
+pvfs2-server application once it's running, you need to issue a
+\texttt{killall pvfs2-server.bin} command instead of the more common
+\texttt{killall pvfs2-server} command.
+
+\subsection{Why do you single out Redhat users?  What's so different
+  about Redhat than other distributions?}
+
+Some Redhat version (and probably some other less popular
+distributions) use a heavily modified Linux 2.4.x kernel.  Due to the
+changes made in the memory manager and signal handling, our default
+Linux 2.4.x kernel module will not even compile!  We have
+compatibility code that can mend the differences in place, but we have
+to be able to detect that you're running such a system.  Our configure
+script tries hard to determine which version you're running and
+matches it against a know list.  If you suspect you need this fix and
+our script does not properly detect it, please send mail to the
+mailing list and include the contents of you /etc/redhat-release file.
+
+In addition, some Redhat versions ship with an NPTL (threading
+library) implementation that PVFS2 is not compatible with.  We cannot
+explain why the errors we're seeing are occuring, as they appear to be
+in glibc and the threading library.  In short, we disable the use of
+the NPTL on these few Redhat systems.  It should be noted that we are
+fully compatible with other distributions that ship NPTL libraries
+(such as Gentoo and Debian/unstable).
 
 %
 % REDUNDANCY



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