*** ABOUT SCSIPROBE 3.5

Alliance Power Tools™ 2.7.2 supports the new SyQuest/SCSIProbe Driver Compliance Standard specified by SyQuest in January, 1993.  To understand what this means to you, a little background information is in order.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Quoting from "SCSIProbe Driver Compliance Guidelines" by Robert Polic:

"The way the Macintosh OS currently works, the SCSI bus is scanned on startup for devices with drivers and the drivers are loaded.  Once a driver is loaded, the OS has no mechanism for unloading it.  This works fine for fixed media devices such as hard drives which stay mounted until the system is restarted, but for removable media devices this becomes an issue because coherency between driver and media is lost the first time a disk is ejected and replaced with another disk formatted by a different vendor.

"It is important to maintain the coherency between driver and media in order to avoid data corruption or system errors.  By mixing drivers and disks, the user is at risk because "Driver A" doesn't necessarily understand how to access "Disk B".

"Currently there is no OS mechanism to maintain the coherency and this is the source of most end-user frustrations, especially bureaus and copy shops that deal with large numbers of cartridges from many different sources."

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

In short, if users mixed cartidges formatted with different driver/formatting software (i.e. APT, SilverLining, HDT FWB, Drive 7, etc.) users often experienced driver compatibility problems because the Macintosh doesn't "forget" the drivers when cartridges have been ejected.

To solve this problem, SyQuest developed a compatibility compliance standard in conjunction with SCSIProbe 3.5 to clear the driver from memory when the cartridge is ejected, thereby insuring that memory-resident drivers don't conflict with one another or with the inserted media.  To set this option, open SCSIProbe from your Control Panels and click the "Options" button.  You will be presented with the following options:

INSTALL VOLUME MOUNTING INIT - when the box is checked, SCSIProbe installs a user-selectable keystroke combination that tells the Macintosh to mount any cartridges not appearing on the desktop.  The default mount key is Command-Spacebar.

CLOSE DRIVER AFTER EJECTING - when this option is checked, SCSIProbe tells the Macintosh to clear the driver from memory when a cartridge is dragged to the Trash.  If it is not checked, the driver will remain loaded in memory.  If other cartridges are loaded that were formatted with a different driver, their drivers will also load into memory.

MOUNT VOLUMES DURING STARTUP - when this option has been selected, the Macintosh will attempt to mount volumes on startup.  This may sound redundant since the Macintosh will mount all available drives at boot time, but some drives (like SyQuests) aren't always ready when the Mac is first turned on and would normally be mounted by this procedure.  By marking this box, SCSIProbe will try to mount volumes later during the startup process.

*** Using SCSIProbe with SyQuest cartridges

When a SyQuest cartridge has been mounted, the driver is loaded into memory.  If the "Close Driver After Ejecting" box in SCSIProbe was marked at boot time, the driver will be removed from memory when the cartridge is dragged to the Trash.  When a new cartridge is inserted, it will not automatically mount.  To mount it, either click the "Mount" button in SCSIProbe, or type the Mount Key combination (Command-Spacebar, or the combination you have entered in the "Mount Key" box of SCSIProbe).  You can also mount it using the Alliance Power Tools "Mount" command.

If you would prefer that the cartridge mounts itself automatically, DO NOT mark the "Close Driver After Ejecting" box.  Note, however, that if you are using cartridges formatted by different formatting/driver software, their drivers will accumulate in the Macintosh's memory, and may lead to driver conflicts.  If all of your cartridges are formatted with Alliance Power Tools 2.7.2 (or later), there is no need to worry about this problem.

*** Comments

If you are not using SCSIProbe, cartridges will will behave as if the "Close Driver..." box was not checked.  Their drivers will remain loaded in memory.  Cartridges can be mounted using Power Tools Assistant™, and any cartridges inserted after the first one has been mounted will all mount themselves automatically.  Note:  inserting cartridges formatted by different formatting/driver software may result in incompatibilities, system errors, or possible data corruption.  APS recommends that all cartridges (as well as your other hard drives) be formatted by Alliance Power Tools whenever possible to avoid this possibility.