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From: balon@hpcupt1.cup.hp.com (Tom Balon)
Newsgroups: comp.unix.internals
Subject: File System and ZBR disks
Message-ID: <68020001@hpcupt1.cup.hp.com>
Date: 23 Apr 91 18:47:31 GMT
Organization: Hewlett Packard, Cupertino
Lines: 27




	How do different versions of unix deal with new ZBR (Zone Bit
	Recording)) style disk drives. These drives are divided into 
	several zones with a different number of sectors/track in each 
	zone. 

	As I understand it, the unix file system uses the track size,
	block/frag size, and information from the super block ( rotdly
	for example ) in order to optimally allocate the next disk block.
	This may not work well with ZBR. For example, say we have a
	disk with 1 to n zones. We build a 8K/1K file system on the disk.
	In zone 1, the track size is 32K so we have 4 8K blocks per track,
	in zone n, the track size is 24K so we have only 3 8k blocks per
	track. Under these conditions, the old algorithm breaks down.

		
							- Tom


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