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Network Support Encyclopedia 9
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cmpvrp.txt
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1992-03-16
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COMPSURF:
Formatting and testing disk drives is performed by NetWare's Compsurf.
When initialized, Compsurf "finds" the disk(s) in the system. If an XT
(80x8 CPU), the controller ROM is examined; if an AT (80x86 CPU), the CMOS
is searched; if the DCB (Novell's Disk Coprocessor Board) is used, it is
searched; and finally, if a Value Added Disk Driver (VADD) is used (NetWare
2.1x), the VADD's routines will search for drives.
There are nuances in the usage of Compsurf. First, if the drive being
formatted/tested is defined in the CMOS of an AT, the FORMAT (really a
low-level format*) option should NOT be used. Rather, the manufacturer's
low-level format routine should be used. This is due to the way Compsurf
operates. On every option but drives defined in the AT's CMOS, Compsurf
issues a single format directive and the controller proceeds to format the
drive and reports back to Compsurf when it is done. On the drives defined
in the CMOS, Compsurf must issue thousands of format commands. This is due
to the unusual design of the AT's disk controller, the controller is only
able to format one track at a time (not cylinder <the same track on each
platter side>, track) and, in this case, Compsurf does not always produce an
ideal format, that is why the manufacturer's routines are recommended.
Footnote:
*low-level format - when the disk controller writes a sequence of address
and control information at the beginning of each sector of the hard disk;
This is performed so that the controller will be able to locate each sector
on the disk.
The testing that Compsurf provides is acceptable, but, with the advent
of every current version of NetWare incorporating SFT level I (HOTFIX), the
testing performed by Compsurf isn't needed beyond a couple of passes (taking
approximately 1-3 hours). The couple of passes are necessary because during
the installation process the HOTFIX option is NOT in operation. Running the
operating system (NET$OS) incurs the action of HOTFIX, but, this isn't
possible during the system installation. If a bad disk spot is encountered
during this procedure it can hamper system installation. On versions of
NetWare not using SFT (pre 2.1x only), Compsurf should be run longer for a
more complete diagnosis of the disk.
The use of Compsurf should be limited to disks being installed into the
file server.
VREPAIR:
Repair of the File Allocation Tables (FAT) and Directory Tables as well
as the remapping of bad blocks are provided by NetWare's VREPAIR. For
Advanced NetWare versions 1.0 on up, VREPAIR replaces the VOLFIX utility
that came with NetWare.
(some technical notes:)
Things that can cause errors which might incur the need of disk maintenance:
1) use of a DOS partition that occupies the last cylinders of a disk using
NetWare with/SFT; the problem involved is the trashing of data in the
redirection blocks NetWare uses but DOS doesn't understand, so DOS writes
over them, thus destroying parts of your data in the NetWare partition. One
possible solution would be to reduce the high cylinder number DOS occupies
by 5 or so. The preferred solution is to remove the DOS partition
altogether!
2) here is a fictitious possibility: you may get data errors on the disk
(such as IO error during random read or write errors at sector xxx), if you
have a SFT system, chances are you have a RAM problem <bad, or power problem
manifesting itself as a RAM problem>, a bad disk controller or a bad network
card, there are other reasons, but, most importantly, the disk surface most
likely isn't involved, unless the disk wasn't properly low-level formatted
before installation as a NetWare drive
3) on non-SFT systems, the development of a bad sector <a legitimate excuse>
a bad sector is noted if the error persists, is recreatable (the error) and
sometimes can be overcome by multiple retries.
4) On any system, SFT or not, FAT and/or Directory errors (the type found
during initial bootup), any error except the one that includes "marked used
with no file" which is NOT an error, but, rather a for your information
message and the reason for that message's presence will be erased as the
disk is used (once the server is booted)