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Disk Mode
Working With Partitions
Managing a SCSI Chain that Includes a Computer
If you create a SCSI chain that contains both a K2661 and a computer, you’ll need to use caution
to prevent file corruption. We’ll explain how this risk of file corruption occurs, then describe
how to avoid it.
When you boot up your computer, it addresses the SCSI devices to which it’s connected, and
attempts to mount every SCSI device whose format it recognizes. While mounting a disk, the
computer examines the disk’s file allocation table (FAT). The FAT contains the locations of all the
data on the disk. Consequently, the FAT gets updated every time you write data to the disk.
Here’s where the risk of file corruption occurs.
When you write to your hard disk from the K2661, the K2661 updates the disk’s FAT. But there’s
no way to instruct the computer that the FAT has been changed, so the K2661 and the computer
have different versions of the disk’s FAT. If you write to the disk from the computer at this time,
you run the risk of writing over the data you just stored from the K2661.
You can eliminate this risk by ensuring that the K2661 and the computer have the same version
of the disk’s FAT before writing from the computer. The most foolproof way to ensure this is to
adopt the following rule: Whenever you write to the hard disk from the K2661, unmount and
remount that disk before writing to it from your computer. If it’s a removable-media drive,
ejecting the disk and reinserting it will update the computer’s version of the FAT.
You might be able to unmount and remount the hard disk from the desktop, or using a software
utility—or you might have to restart the computer. If you’re using Windows, you can probably
designate the hard disk as a removable-media disk (as described below), which is convenient
because Windows machines always read the FATs of removable-media disks before writing to
them.
Designating a Disk as a Removable-Media Disk (Windows only)
1. On your PC, run the Device Manager.
2. Expand the Disk Drives category.
3. Double click icon for the K2661's internal hard disk to bring up the Properties dialog.
4. Select the Settings tab.
5. Check the Removable checkbox.
Configuring Device Drivers (Windows 95 and 98 Only)
PCs running Windows 95 or Windows 98 require a SCSI driver for every device in a SCSI chain.
There is no SCSI driver for the K2661, because it’s not required for normal SCSI operations.
Consequently, the first time you boot up your PC after connecting it to the K2661 via SCSI, you’ll
need to do some configuring to enable the PC to recognize the K2661. This configuration isn’t
required, but it enables the PC and the K2661 to interact more smoothly.
A Bit of Background
When you start up your PC, Windows scans the PC’s SCSI port(s) for connected devices. For
each SCSI device it finds, Windows checks a set of entries in the Device Manager, to verify that
the appropriate SCSI drivers are installed. Windows 95 and 98 require that the Device Manager
contains an entry for each SCSI Logical Unit of each SCSI device. The K2661 has eight possible
SCSI IDs (0–7), so your Device Manager should contain eight entries corresponding to the
K2661. Each of these entries must specify a valid SCSI driver—otherwise Windows will report
one or more unknown devices as it boots up.
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