

                           TECHNICAL BULLETIN
                             Bulletin #1-265

Date:  March 23, 1990

                       Mirroring Large Disk Drives

Traditionally, NetWare 286 volume information tables have resided on
sectors 16 and 17.  These sectors are automatically mirrored in NetWare
286.  As disk drives have increased in capacity, so have the volume
information tables.  Disk drives larger than 600MB store the volume
information tables on sectors 22 through 25, as well as on sectors 16 and
17.  However, sectors 22 through 25 are not remirrored through the REMIRROR
command, or through auto-remirror.  Thus, if the primary disk fails, the
volume information table on sectors 22 through 25 will be lost when the
primary disk is replaced.  This will result in "Data Mirror Mismatch"
errors when booting the file server.

To prevent these problems on disks larger than 600MB, Novell has placed an
operating system patch on NetWire that provides disk mirroring for sectors
22 through 25.  The name of the patch file is 215MIR.ZIP.  Use PKUNZIP.EXE
to extract all the files from 215MIR.ZIP.  The READ.ME file included in
215MIR.ZIP contains proper documentation for executing the patch.  Read the
instructions carefully before proceeding.



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