Subject: Re: DEV_B_SIZE
To: Steve Byan <>
From: None <>
List: tech-kern
Date: 01/31/2003 17:50:53
In message <>, Steve Byan writes

>I'd appreciate hearing examples where hiding the underlying physical 
>block size would break a file system, database, transaction processing 
>monitor, or whatever.  Please let me know if I may forward your reply 
>to the committee. Thanks.

If by "hide" you mean that there will be no way to discover the
smallest atomic unit of writes, then you are right: it would be bad.

Provided we can get the size of the smallest atomic unit of writes
in a standardized, documented, mandatory way, we will have no problem
coping with it: Using a 4k size is no problem for our current
filesystem technologies and device sizes.

It was my impression that already many drives write entire tracks
as atomic units, at least we have had plenty of anecdotal evidence
to this effect ?


(FreeBSD's disk-I/O wizard)

Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.