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Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cornell!uw-beaver!ubc-cs!van-bc!
From: lphillips@lpami.wimsey.bc.ca (Larry Phillips)
Newsgroups: comp.sys.amiga,comp.sys.amiga.tech
Subject: Re: FFS details
Message-ID: <704@lpami.wimsey.bc.ca>
Date: 17 Aug 89 21:50:31 GMT
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To: van-bc!rnews

In , cire@dustbin.cisco.com (Eric B. Decker) writes:
>2) Where can I find detailed specifications of the FFS?

I don't know of anywhere you can find the details offhand, but here are all the
differences I know of between the old and new file system.

--------------------

Block 0 (Cyl 0, Head 0, Sector 0 on any partition), contains:

OFS:  'DOS',0
FFS:  'DOS',1

--------------------
Root block:

FFS can have an extension to the bitmap pointer table. The pointer to the next
sector containing pointers to bitmap pages is contained in longword $68

--------------------

Hash chain extensions are sorted in increasing order of blocks pointed to.

--------------------

File data blocks contain  512 bytes of data, with none of the overhead
contained in the OFS scheme. This results in a tradeoff. You trade considerable
speed for less recoverability.

--------------------

-larry

--
"So what the hell are we going to do with a Sun?" - Darlene Phillips -
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|   //   Larry Phillips                                                 |
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