Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!samsung!uunet!p4tustin!carl From: carl@p4tustin.UUCP (Carl W. Bergerson) Newsgroups: comp.os.msdos.misc Subject: The 33 MByte limit (was: Trouble installing DOS 4.01) Message-ID: <3367@p4tustin.UUCP> Date: 2 May 91 16:35:33 GMT References: <1991Apr20.061909.24406@leland.Stanford.EDU> Distribution: na Organization: POINT 4 Data Corporation, Tustin, CA Lines: 53 garygm@leland.Stanford.EDU (Gary Brainin) writes: > > I have a no-name ("IPC") 386 which currently has DOS 3.3 on it. > Feeling constrained by the 35MB limit on my hard drive . . . Why do you feel constrained by the 33 MByte limit? Do you have any one file that is greater than 33 MBytes? If not, then you ought to use DOS 3.30 to partition your disk into smaller chunks. Why? For efficiency. Let me explain a little. When you access a file, DOS looks at the directory entry and the FAT. The FAT is stored on the first cylinder of the partition and the directory entry and the file itself are stored SOMEWHERE. Now, if you partition your disk into two equal sized partitions and if you spread your applications and files equally between the partitions, the distance from the FAT to SOMEWHERE will be about 1/2 what it would be if you had one humungous partition. Looking at it slightly differently, if you have a disk with a track to track access of 4 ms and an average access of 28 ms, partitioning it into 2 halves would change the effective average access to 16 ms ((28-4)/2)+4 ms. Of course to achieve some substantial portion of this theoretical improvement you need to give some thought as to which partition you place individual applications and files. For example, I make sure my C compiler, libraries, include files, sources, and the tmp directory are all on the same partition, but if I have two physical disks I move the tmp to the second disk. I don't worry about where my editor is, because it is only read from the disk when I start a session and it is never referenced (from disk) again (unless it's some gigantic program with overlays, but I wouldn't use an editor like that for programming). BTW, using the various performance testing programs, such as Norton or Coretest usually will not show a performance improvement because they seem to access the physical information DOS has about the disk not the logical information stored in the partition table. flame off really big FLAME ON type file | more - but that's another story really big FLAME OFF Carl -- Carl Bergerson uunet!p4tustin!carl Point 4 Data Corporation carl@point4.com 15442 Del Amo Avenue Voice: (714) 259 0777 Tustin, CA 92680-6445 Fax: (714) 259 0921