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From: citdem@UAVAX0.CCIT.ARIZONA.EDU
Newsgroups: comp.sys.next
Subject: SR2.0 BuildDisk vs SR2.1BuildDisk
Message-ID: <009472C9.1FEB89E0@UAVAX0.CCIT.ARIZONA.EDU>
Date: 15 Apr 91 09:41:10 GMT
Reply-To: citdem@UAVAX0.CCIT.ARIZONA.EDU
Distribution: na,local
Organization: University of Arizona
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History: When I got 2.0 a couple of months ago, I installed it via BuildDisk.
         To my surprize, the post-build "available" space on my HD was 635MB
         instead of the 662MB I expected.  Having never checked "available"
         space, I assumed BuildDisk walloped my HD.  However, the real
         problem was that I had a HP hard disk (635MB) not a Maxtor (662MB).
         NeXT replaced the HD and the replacement had 662MB "available".

Now: Because I got SR2.1 on OD, I had to rebuild my HD once again.  And once
     again, a surprize.  Instead of the expected 662MB, I have 653MB
     "available".  I noticed that NeXT has changed the number of cylinders
     per cylinder group from 32 to 16.  I noticed most other numbers halved
     or doubled - except the "i/g" number which is reduced by about 1/4.
     If "i/g" means i-nodes per (cylinder) group, does this mean that I now
     have more inodes and, hence, more space is devoted to "administrative
     overhead"?  BTW, I think NeXT changed the number of cylinders per group
     so that one i-node would fit on a page of memory.  (In SR2.0 NeXT
     wanted 4096 bytes per i-node; but BuildDisk changed that to 5000+ bytes.)

This is just speculation on my part.  I am new to NeXT and Unix.  Anyone got
better info - the REAL explanation.  Should I get any better I/O times?  Is
more memory now available for use?  (BTW, reloading SR2.0 yields the original
662MB.)

Don McCollam  (citdem@uavax0.ccit.arizona.edu)