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Tristrami May 10, 2001 01:31 PM
HD for Power Mac 8100
I'm looking for a replacement Hard Drive for a Power Mac 8100. Any recommendations for whare I can find a good but inexpensive one? Also, I think it takes a 50-pin SCSI, but what's the difference between SCSI-1, SCSI-2 & SCSI-3?
Walter J. Ferstl May 10, 2001 07:02 PM

look for a drive with the following specifications:
SCSI up to ultra (not ultra wide) which is basically the same as SCSI-2.
Rotational speeds should be 5400 rpm, maybe 7200. Form factor, of course, 3.5 inch, height 1" or less. SCSI-2 is what you would get as the entry point for an affordable hard drive today. That means a 50-pin interface, too.

The 8100 has a 50-pin SCSI connector internally. If you want to have more than one drive internally some day (there is rooms for one more drive inside the 8100), you should choose a *true* 50-pin drive to start with. Due to termination problems, avoid drives that are *adapted* down to 50-pin from 68-pin (ultra wide) or 80-pin (SCA) interfaces even if they are cheaper.

SCSI-3 is 68-pin which cannot be used in an 8100 internally without an additional SCSI card (ultra2/LVD/160).

Find some good information on SCSI in Macs here:

More general info on SCSI:

If the drive you choose is larger than 2 GB, make a startup partition with 2 GB or less. Depending on the version of your Mac OS you use, 2 GB will be the maximum for the partition where the system folder resides (that applies to 7.6, maybe for 8.1 too).

I have very good experience with IBM drives, such as the DCAS 34330 (4.5 GB) which is very quiet and reliable. It is a 50-pin, ultra drive.

I have bought most of my hard drives from Smalldog ( as well as from Other World Computing ( OWC has more offerings for internal and older-style drives, however, which is the sort of drive you are looking for, at very good prices.

Best regards,

ddiokno May 10, 2001 10:24 PM
OtherWorld Computing always has good supply of SCSI drives... check them out...
good luck
ddiokno May 10, 2001 10:25 PM
Originally posted by ddiokno:
OtherWorld Computing always has good supply of SCSI drives... check them out...
good luck
Whoops, sorry Walter, read over your post too quickly and missed the reference to Other World at the bottom....
Tristrami May 10, 2001 11:26 PM
Walter, Dave - Thanks for the great advie and thoughtful explanations. I'm not sure if this is the right forum, but can you tell me a little more about HD partitioning and some of the whys and hows behind it. What are the ideal partition sizes for OS 9 & 0S 8.5? I have a 30gb unpartitioned drive in my 5400 that seems to work beautifully. What benefit(s), if any would I receive if I were to create a startup partition/partition it?

PM 5400/G3 400
Performa 6116CD
Walter J. Ferstl May 11, 2001 05:47 AM

most of the generally agreed partitioning considerations with Macs apply to the HFS formatting scheme (as opposed to HFS plus, a.k.a. HFS+). HFS has been and still is the legacy formatting scheme, readable and writable on most Mac systems in use today, old and new (HFS is *not* usable for Mac OS X, however). I think HFS is useful for systems 6.x up to OS 9. I am sure for the 7.0 to 8.5 range which I am running on my machines.

In HFS, there is a term called "block size" which means the smallest unit that can be utilized by the system on a hard drive. For an unpartitioned but already properly formatted drive, imagine it as a single partition. Now, the block size is a certain proportion of the partition size - that means that in a big partition the block size will be bigger than in a small one. Example: For a partition of 2 GB, the block size will be 33 kB, that means any file will take up at least 33 kB on the partition, even if is just 2 kB on a floppy disk. In a partition of 700 MB, block size is around 9 kB.

So if you have many small files to deal with, a smaller partition will be more economical in terms of hard drive space. If you are doing text processing using a text editor that has little formatting overhead (i.e., basically any text processor except Microsoft«s) and you produce a lot of small files like letters etc., partitioning will be an issue. For a photoshop professional, partitioning a huge drive will not be an issue at all. Thus it all depends on your usage of your Mac as a whole.

The HFS+ scheme, available only from Mac OS 8.0 up, does not have a fixed minimum block size. If you connect an HFS+ formatted disk to a Mac running under System 7.x, the drive and its data will not be usable. Maybe you will even get a message like "do you want to format this drive?" - but I never tried this.

Starting with Mac OS 8, you have the choice to make partitions on a drive either in HFS or in HFS+ style. As far as I know, you can partition a drive to some HFS partitions along with one or more HFS+ partitions, if you like.

Hope this helps,

good luck,

ddiokno May 11, 2001 03:13 PM
Hi Tristami,
The forum for this question would be the Peripherals forum, but not a problem here since it is within this thread :-) Another potential reason to partition would be to intall different operating systems to boot into ie 7.5, 8.0, 8.5, 9, etc..., to use one as a utility partition (make it smaller/bootable) which you could boot and then run diagnostics like Norton, Techtool, etc from on your main partition AND also defrag main/others... another reason I sometimes partition a machine is if I want to create restore CD's, I'll save the drive image to one of the partitions and make the restores cd from that partition...
good luck,
ddiokno May 11, 2001 06:23 PM
One thing to be careful about with the 7200 RPM and faster (there are also 10000RPM drives) is the heat that they generate.... quite a bit of hear. I used to have a PowerComputing PowerTower and it came with 7200 RPM AV drive, which would occasionally freeze/lock-up because the drive would get so darned hot...
just something to consider...
one more thought... I believe the 8100 has standard scsi, not fast, wide, ultrawide, or any of the other types of scsi, so don't get caught up in buying any of those types of drives (and paying tons extra) to use an adapter, because your bottleneck will be your scsi.... May 11, 2001 09:45 PM
If heat is really an issue, you could always tack on a 2nd fan (you see people do that every once in a while). I know that people who have done this say it's no big deal, but I personally haven't done it (yet).

Robert Accettura
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