Coda File System

Re: Few Basic Coda questions...

From: SOM Bandyopadhyay <>
Date: Thu, 27 May 1999 22:53:30 -0600
Some more comments below within "  ...." ...thanks, som.

"These are absolutely my opinion. My opinion
  do not represent those of my employer"

>>> Marc Schnieder <> 05/27 3:47 PM >>>
SOM Bandyopadhyay wrote:

> 4. How is CODA client's performance when using Windows explorer and
browsing the network? Does Venus tries to bring the entire file when
explorer does a FIND_FIRST/FIND_NEXT operation? If so, isn't there a
heavy degradation of performance?
> 5. What is the Win32 function call on which Venus starts caching the
entire file? Is it Win32 Open? Find_FIRST/FIND_NEXT? or something else?

Venus caches entire files when they are opened by an application. In
windows this is done by the CreateFile Win32 API function. The
FindFirst/Next functions search for files and are called by the
explorer to browse directories. Calling these functions does not cause
Venus to fetch the files from the servers. Directories however are
fetched and cached since they need to be opened to be read.

Overall it depends on the user level application (in this case Windows
Explorer) if the files are cached (opened) during browsing
Binaries (i.e. .exe files) will be opened by the explorer to extract
icon. This will cause Venus to fetch the file.

If there are many large binary files in a directory that is listed by
the explorer you will see performance degradation. In fact, the system
might be unusable when working on a weak network. 

=====>" Browsing the network with huge number of binary files may be a
common activity of windows users. User may just browse the directory to
look for some information, but never execute any of those
programs...bringing down those large binaries may really slow down the
performance without any gain ( I mean no cache hit in near future ). 

Is there any interest to solve this problem? Any ideas?"

But if the files are
hoarded/cached and the kernel cache has been warmed up, Coda is faster
than Samba and in certain scenarios even than the local disk.

===> "I understand after the first time cache by Venus next access to
files will be faster compare to any other protocol hitting wire. But I
don't understand how its faster compare to local disk browsing. Is there
something I am missing?"

Received on 1999-05-28 00:55:15