NOVELL TECHNICAL BULLETIN

          TITLE:  Recommendations on the Use of ISADISK.DSK
   DOCUMENT ID#:  TB.P.302
           DATE:  August 7, 1992
        PRODUCT:  NetWare
PRODUCT VERSION:  3.11
     SUPERSEDES:  None

        SYMPTOM:  "Unexpected Error 22 (89F0)" at login time
		  Possible data damage
		  Any other symptoms of erratic disk controller behavior

ISSUE/PROBLEM

The symptoms above have occurred when running the driver ISADISK.DSK (dated 2-15-91) on a NetWare v3.11 file server operating with ESDI or IDE/ATA hard drives.

When this driver is loaded on the NetWare v3.11 server, it goes through the following steps by default:

*	It "sets up" the hard drive with best-guess, universal parameters (3 heads, 17 sectors per track) to initially communicate with the drive.

*	It then looks for a NetWare Ready (NR) or Common Configuration Method (CCM) stamp on the drive.

The driver's next step is one of these two possibilities:

1)	The NR or CCM stamp is found and the drive is set up a second time using the parameters found in the stamp.

2)	No NR or CCM stamp is found and ISADISK.DSK then uses the INT41/INT46 vectors to obtain the correct drive information from the BIOS and to set the drive up a second time with those parameters.

In either of these two cases, ISADISK.DSK sets up the drive more than once.  However, the user may load this ISADISK.DSK with the "/b" option, which bypasses the search for the NR or CCM stamp on the disk by using the INT41/INT46 vectors to set up the drive only one time with information obtained from the BIOS.

The symptoms listed at the beginning of this bulletin occur as a result of certain controllers not being properly equipped to handle the multiple setups of the drive.  When such a controller is set up more than once, it operates in an erratic fashion and often corrupts data on a drive.  This may include irreparable damage to partition information or to critical system files.

SOLUTION

Systems having suffered data corruption due to an erratic controller must have the corrupt data removed.  In most cases, this means recreating any partitions on the drive and restoring all data from a clean backup.  Once the drive's partitions have been recreated, the user can load the ISADISK.DSK (dated 2-15-91) with the "/b" option only.  Novell recommends, however, that instead of relying on the "/b" option, the user should follow one of two courses of action.

1)	Obtain and load the new ISADISK.DSK (dated 6-17-92 or later), which is available in the downloadable file ISA311.ZIP.  This updated driver corrects the problem of multiple setups by making the BIOS call by default, and by foregoing the check for an NR or CCM drive stamp, thereby only setting up the drive once.

2)	For IDE/ATA drives, unless otherwise specified by the hardware manufacturer, the user should use the driver IDE.DSK, dated 1-09-92 or later (available in IDE386.ZIP).  (Warning:  The partition table created by the IDE disk driver may not be compatible with that of the ISADISK.DSK driver.  Therefore, data loss may occur if the user switches to the IDE.DSK from ISADISK.DSK.  In all cases, a full system backup is recommended.)

In situations where a user wants the new ISADISK.DSK to obtain drive information from an NR or CCM sector, the "/n" option may be used.  This option requires ISADISK.DSK to initialize the drive as it did previously.  However, using this option means that multiple drive setups will occur and the user should be aware that if a controller is not equipped to handle these multiple setups the same symptoms as those above may result.  When in doubt, the user can contact the controller manufacturer or the dealer from whom the controller was purchased.

Summary of ISADISK.DSK Options

ISADISK.DSK Version   "/b" load option	  "/n" load option   "/l" load option*
------------------------------------------------------------------------------
      2-15-91            available           DEFAULT            available
                        lowercase only    (not available)      lowercase only

  6-17-92 or later        DEFAULT           available           available
                       (not available)   non-case sensitive    lowercase only

*The "/l" option permits ISADISK.DSK to look below memory address F0000h on controllers set at I/O = 170h.  If the I/O address of the controller is 1F0h, the "/l" option is unnecessary.

ISA311.ZIP and IDE386.ZIP are available from Novell Authorized Resellers.  The drivers are also available in the Professional Version of the Novell Network Support Encyclopedia and on NetWire (CompuServe) in Forum NOVLIB, Library 04.  Or select the Service and Support icon in NetWare Express (GE Business Talk).