papa@pollux.usc.edu (Marco Papa) (03/10/88)
A while ago there were requests on information about large (> 100 Meg) hard disks compatible with the Amiga. The last issue of InfoWorld (March 7, 1988) features a "Product Comparison" of a number of such disks compatible with the IBM and Macintosh. This includes ST506/MFM, ST506/RLL, ESDI, and SCSI disks. Some of them should be compatible with the current Amiga controllers (ST506/MFM and SCSI). These are AT-compatible [not clear whether half-height or full-height, the latter ones not Amiga-compatible]: CMS Enhancements F120 AT-P ST506 Micropolis 1375 PC Pak SCSI Storage Dimentions AT120 ST506 Storage Dimentions AT115 SCSI These are Mac-compatible, either half-height internal drives or external drives [which one could connect to the A2090 external SCSI connector]. Bering Totem SCSI CMS Enhancements SD140K SCSI Jasmine Direct Drive 160 SCSI Rodime 100 Plus SCSI Rodime 140 Plus SCSI Supermac Dataframe XP150 SCSI The article also quickly covers "bigger" drives (300M and up), and gives an introduction to the various interfaces (ST506/MFM/RLL/ESDI/SCSI) if you hadn't heard enough of it :-) -- Marco
th@cup.portal.com (03/11/88)
I haven't found ANY limitation re: the size of a hard disk one can place on the Amiga (yeah, I'm the guy with the > 1GB Amigas). HOWEVER, there *IS* the brain-damaged 50MB partition size limitation on the Amiga which totally prevents the Amiga being used in any real application by any of my customers. My customers do NOT have or use the "toy" 200 record or memory-resident DBMS products which seem to be proliferating nowadays. So where does the 50MB limit come from? Simple. Get out your calculators. Look at the format of the root block: there is a list of 26 "pointers" to the bit map pages. Each bitmap "page" has 127 longwords of bits and one longword of checksum. Each longword has 32 bits. So: 26*127*32 is the LIMIT to the numbers of sectors AmigaDOS can handle on a hard disk. Until this LIMIT is removed, the Amiga's filesystem is as BAD as the 32MB limit on MS-DOS partitions. 100MB and larger data bases are NOT unreasonable. Partitions are ludicrous. Do YOU have partitions on your mainframes? With a bank of Maxtor XT2190s on each Amiga, the limitation is crippling. WHY isn't the list of bit maps an open-ended chain? Haven't heard that the alleged "Fast File System" (FFS) will correct this glaring deficiency; does anybody KNOW if it will?
page@swan.ulowell.edu (Bob Page) (03/12/88)
The partition limit is 2GB. There's a bug in the old file system with respect to the protection bits ... the root block doesn't have protection bits, since that's where the bitmap pointers are, but the current file system didn't take care of that (reportedly a sign problem) and clobbered the bits there, so the only partition you were safe with was one under 54MB. This bug is fixed in FFS, and the partition limit is now really 2GB. ..Bob -- Bob Page, U of Lowell CS Dept. page@swan.ulowell.edu ulowell!page "I don't know such stuff. I just do eyes." -- from 'Blade Runner'
jesup@pawl14.pawl.rpi.edu (Randell E. Jesup) (03/12/88)
In article <3822@cup.portal.com> th@cup.portal.com writes: >So where does the 50MB limit come from? Simple. Get out your calculators. >Look at the format of the root block: there is a list of 26 "pointers" to >the bit map pages. Each bitmap "page" has 127 longwords of bits and one >longword of checksum. Each longword has 32 bits. So: 26*127*32 is the >LIMIT to the numbers of sectors AmigaDOS can handle on a hard disk. ... >WHY isn't the list of bit maps an open-ended chain? Haven't heard that >the alleged "Fast File System" (FFS) will correct this glaring deficiency; >does anybody KNOW if it will? I've said this before, but.... They tried to fix the bitmap page limit in 1.2. I think the last link is to another page of bitmaps, etc. Unfortunately, another new thing in 1.2, the archive bit, happens to live where they put the pointer, if it were a directory block instead of the root. So when you change something in the root, the link to the next block of bitmaps gets trashed. Oh well. The FFS (coming in 1.3, in Gamma test now) is 1) FAST! up to 600+ Kbytes/sec, and 2) fixes the partitioning problem, max partition in 2 gig. // Randell Jesup Lunge Software Development // Dedicated Amiga Programmer 13 Frear Ave, Troy, NY 12180 \\// beowulf!lunge!jesup@steinmetz.UUCP (518) 272-2942 \/ (uunet!steinmetz!beowulf!lunge!jesup) BIX: rjesup (-: The Few, The Proud, The Architects of the RPM40 40MIPS CMOS Micro :-)