[Mimedefang] Good Ramdisk Size

Ole Craig olc at cs.umass.edu
Wed Mar 31 10:12:18 EST 2004


On 03/31/04 at 08:56, 'twas brillig and Robert Covell scrobe:
> 
> What is a good ramdisk size for use with MD?  The default on linux is 4096
> but are concerned about those emails that have attachments over 4MB or
> getting several emails that together have attachments greater than 4MB.  We
> set the size to 50MB.  Do we need to do this?  Should we use the default
> ramdisk size (4096) and not worry about it?
> 

Bob -
	I suspect you're confusing the kernel parameter defining
"initial ramdisk size" (CONFIG_BLK_DEV_RAM_SIZE) with the tmpfs David
recommends under linux for higher MD performance. The initial ramdisk
size pertains only to the uncompressed initrd used during system boot;
you should leave it at 4096 unless you can't run mkinitrd without
complaints. While we've all been calling it a "ramdisk" (since that's
the generic term for any section of system memory that's setup to act
as though it were a disk) the tmpfs filesystem is not the same thing
-- among other differences, unused tmpfs space under linux can be
swapped. 

	If you don't pass a size parameter to tmpfs in the mount
command (or in fstab) it defaults to a size equal to half of the
system's installed physical RAM. On a high-RAM server this is probably
in excess of requirements; the most space you'd possibly need for
/var/spool/MIMEDefang would be your max message size
(confMAX_MESSAGE_SIZE) in sendmail times the maximum number of
MIMEDefang slaves you run (-x argument to mimedefang-multiplexor.) Not
even that much is really necessary, unless you tend to hit that
maximum slaves number all the time...


		Ole
-- 
Ole Craig * UNIX, linux, SMTP-ninja; news, web; SGI martyr * CS Computing
Facility, UMass * <www.cs.umass.edu/~olc/pgppubkey.txt> for public key

  Where are the missing deficit-reduction program-related activities?



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