[OpenAFS] Using tmpfs for afs cache

Charles Karney ckarney@sarnoff.com
Mon, 3 Dec 2001 10:08:17 -0500

 > From: David Thompson <thomas@cs.wisc.edu>
 > Date: Mon, 03 Dec 2001 08:26:03 -0600
 > My concern about using ramdisks on linux is that AFAIK linux ram disks
 > use physical (not virtual) memory.  Thus, you partition your memory and
 > prevent the OS from managing AFS cache usage vs. all the other memory
 > demands.  Maybe memory is cheap enough now that it doesn't matter; just
 > buy a computer with a Gig of ram, pay a few extra bucks and go on your
 > happy way.
 > Are any list readers aware of a linux VM based fs, similar to solaris
 > tmpfs?

Recent Linux kernel support tmpfs with semantics similar to Solaris.  This
gets installed by default with RedHat 7.2.  Here is a portion of the
documentation for the kernel configuration:

Virtual memory file system support
  Tmpfs is a file system which keeps all files in virtual memory.

  In contrast to RAM disks, which get allocated a fixed amount of
  physical RAM, tmpfs grows and shrinks to accommodate the files it
  contains and is able to swap unneeded pages out to swap space.

Charles Karney                  Email:  ckarney@sarnoff.com
Sarnoff Corporation             Phone:  +1 609 734 2312
Princeton, NJ 08543-5300        Fax:    +1 609 734 2586