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From: johnl@iecc.cambridge.ma.us (John R. Levine)
Newsgroups: comp.unix.sysv386
Subject: Re: Why do you want a 512 byte block file system anyway?
Message-ID: <1990Nov21.232206.19205@iecc.cambridge.ma.us>
Date: 21 Nov 90 23:22:06 GMT
References: <1990Nov18.182135.17954@scuzzy.in-berlin.de> <1990Nov19.232124.7802@cichlid.com> <1990Nov21.134043.25732@virtech.uucp>
Reply-To: johnl@iecc.cambridge.ma.us (John R. Levine)
Distribution: comp
Organization: I.E.C.C., Cambridge MA 02238
Lines: 27

In article <1990Nov21.134043.25732@virtech.uucp> cpcahil@virtech.UUCP (Conor P. Cahill) writes:
>If most of the files are between 0 and 512 bytes long then the 512 byte
>file system will save you both space and performance.
>
>If most of the files are between 513 and 1024 bytes long, then the 1K
>file system wins both.
>
>If most are between 1025 and 1536, then the 512 byte file system will 
>save you some space, but will probably loose in the performance arena.

Here's some actual data.  I wrote a little awk script that looked at all of
the 20,000 files in my news partition.  It figured out how many blocks,
including indirect blocks, the files would take in a 512 or a 1K file system.
Multiply linked files are double counted, but I don't think that affected
the results much.  And the results, in 512 byte blocks are:

	512 total	192220
	1024 total	210866

That is, a 512 byte file system saves about 10% of the total space.  Not
overwhelming, but significant.  Personally, I'll take the extra performance
of a 1K FFS partition.

-- 
John R. Levine, IECC, POB 349, Cambridge MA 02238, +1 617 864 9650
johnl@iecc.cambridge.ma.us, {ima|spdcc|world}!iecc!johnl
"Typically supercomputers use a single microprocessor." -Boston Globe