From: Albert D. Cahalan (acahalan@cs.uml.edu)
Date: Thu Oct 24 2002 - 00:42:54 EST

While going over the vmstat man page, I spotted this:

       All linux blocks are currently 1k, except for CD-ROM
       blocks which are 2k.

This doesn't seem to be true. I need help determining when
things changed so that I can update the documentation.
I've been checking kernels with commands like this:

dd bs=1024k count=1 if=/dev/cdrom of=/dev/null

Linux 2.4.16 and 2.5.42 both seem to use units of 1024 bytes.
Linux 2.2.18 does something weird, but NOT what is described in
the vmstat man page. With 2.2.18, non-CD blocks are 4096 (!!!)
bytes and CD blocks are indeed 2048 bytes.

I suppose there was an even older kernel, perhaps 2.0.xx,
that did the non-CD blocks in units of 1024 bytes. I can
no longer compile 2.0.xx, so I need some help testing that.

Also, am I right about 2.2.xx kernels? Are any of these
kernels affected by block size of a mounted filesystem?
Does it matter if I use a /dev/raw* device? Does any
kernel use different units for file bodies and metadata?

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This archive was generated by hypermail 2b29 : Thu Oct 31 2002 - 22:00:22 EST