NAME
format —
how to format disk
packs
DESCRIPTION
There are two ways to format disk packs. The simplest is to use the
format program. The alternative is to use the DEC standard
formatting software which operates under the DEC diagnostic supervisor. This
manual page describes the operation of
format, then
concludes with some remarks about using the DEC formatter.
format is a standalone program used to format and check disks
prior to constructing file systems. In addition to the formatting operation,
format records any bad sectors encountered according to DEC
standard 144. Formatting is performed one track at a time by writing the
appropriate headers and a test pattern and then checking the sector by reading
and verifying the pattern, using the controller's ECC for error detection. A
sector is marked bad if an unrecoverable media error is detected, or if a
correctable ECC error too many bits in length is detected (such errors are
indicated as “ECC” in the summary printed upon completing the
format operation). After the entire disk has been formatted and checked, the
total number of errors are reported, any bad sectors and skip sectors are
marked, and a bad sector forwarding table is written to the disk in the first
five even numbered sectors of the last track. It is also possible to reformat
sections of the disk in units of tracks.
format may be used
on any UNIBUS or MASSBUS drive supported by the
up and
hp device drivers which uses 4-byte headers (everything
except RP's).
The test pattern used during the media check may be selected from one of: 0xf00f
(RH750 worst case), 0xec6d (media worst case), and 0xa5a5 (alternating 1's and
0's). Normally the media worst case pattern is used.
format also has an option to perform an extended “severe
burn-in”, which makes a number of passes using different patterns. The
number of passes can be selected at run time, up to a maximum of 48, with
provision for additional passes or termination after the preselected number of
passes. This test runs for many hours, depending on the disk and processor.
Each time
format is run to format an entire disk, a completely
new bad sector table is generated based on errors encountered while
formatting. The device driver, however, will always attempt to read any
existing bad sector table when the device is first opened. Thus, if a disk
pack has never previously been formatted, or has been formatted with different
sectoring, five error messages will be printed when the driver attempts to
read the bad sector table; these diagnostics should be ignored.
Formatting a 400 megabyte disk on a MASSBUS disk controller usually takes about
20 minutes. Formatting on a UNIBUS disk controller takes significantly longer.
For every hundredth cylinder formatted
format prints a
message indicating the current cylinder being formatted. (This message is just
to reassure people that nothing is amiss.)
format uses the standard notation of the standalone I/O
library in identifying a drive to be formatted. A drive is specified as
zz(x,y), where
zz refers to the controller
type (either
hp or
up),
x is the unit number of the drive; 8 times the UNIBUS or
MASSBUS adaptor number plus the MASSBUS drive number or UNIBUS drive unit
number; and
y is the file system partition on drive
x (this should always be 0). For example,
“hp(1,0)” indicates that drive 1 on MASSBUS adaptor 0 should be
formatted; while “up(10,0)” indicates that UNIBUS drive 2 on
UNIBUS adaptor 1 should be formatted.
Before each formatting attempt,
format prompts the user in
case debugging should be enabled in the appropriate device driver. A carriage
return disables debugging information.
format should be used prior to building file systems (with
newfs(8) to ensure that all
sectors with uncorrectable media errors are remapped. If a drive develops
uncorrectable defects after formatting, either
bad144(8) or
badsect(8) should be able to
avoid the bad sectors.
EXAMPLES
A sample run of
format is shown below. In this example (using
a VAX-11/780),
format is loaded from the console floppy; on
an 11/750
format will be loaded from the root file system
with
vax/boot(8) following
a “B/3” command. Boldface means user input. As usual,
“#” and “@” may be used to edit input.
>>> L FORMAT
LOAD DONE, 00004400 BYTES LOADED
>>>S 2
Disk format/check utility
Enable debugging (0=none, 1=bse, 2=ecc, 3=bse+ecc)? 0
Device to format? hp(8,0)
(error messages may occur as old bad sector table is read)
Formatting drive hp0 on adaptor 1: verify (yes/no)? yes
Device data: #cylinders=842, #tracks=20, #sectors=48
Starting cylinder (0):
Starting track (0):
Ending cylinder (841):
Ending track (19):
Available test patterns are:
1 - (f00f) RH750 worst case
2 - (ec6d) media worst case
3 - (a5a5) alternating 1's and 0's
4 - (ffff) Severe burnin (up to 48 passes)
Pattern (one of the above, other to restart)? 2
Maximum number of bit errors to allow for soft ECC (3):
Start formatting...make sure the drive is online
...
(soft ecc's and other errors are reported as they occur)
...
(if 4 write check errors were found, the program terminates like this...)
...
Errors:
Bad sector: 0
Write check: 4
Hard ECC: 0
Other hard: 0
Marked bad: 0
Skipped: 0
Total of 4 hard errors revectored.
Writing bad sector table at block 808272
(808272 is the block # of the first block in the bad sector table)
Done
(...program restarts to allow formatting other disks)
(...to abort halt machine with ^P)
DIAGNOSTICS
The diagnostics are intended to be self explanatory.
Warning: These instructions are for people with 11/780 CPUs.
The steps needed for 11/750 or 11/730 CPU's are similar, but not covered in
detail here.
The formatting procedures are different for each type of disk. Listed here are
the formatting procedures for RK07's, RP0X, and RM0X disks.
You should shut down UNIX and halt the machine to do any disk formatting. Make
certain you put in the pack you want formatted. It is also a good idea to spin
down or write protect the disks you don't want to format, just in case.
Load the console floppy labeled, “RX11 VAX DSK LD DEV #1” in the
console disk drive, and type the following commands:
>>>BOOT
DIAGNOSTIC SUPERVISOR. ZZ-ESSAA-X5.0-119 23-JAN-1980 12:44:40.03
DS>ATTACH DW780 SBI DW0 3 5
DS>ATTACH RK611 DMA
DS>ATTACH RK07 DW0 DMA0
DS>SELECT DMA0
DS>LOAD EVRAC
DS>START/SEC:PACKINIT
Follow the above procedures except that the ATTACH and SELECT lines should read:
DS>ATTACH RH780 SBI RH0 8 5
DS>ATTACH RP0X RH0 DBA0 (RP0X is, e.g., RP06)
DS>SELECT DBA0
This is for drive 0 on mba0; use 9 instead of 8 for mba1, etc.
Follow the above procedures except that the ATTACH and SELECT lines should read:
DS>ATTACH RH780 SBI RH0 8 5
DS>ATTACH RM0X RH0 DRA0
DS>SELECT DRA0
Don't forget to put your UNIX console floppy back in the floppy disk drive.
SEE ALSO
bad144(8),
badsect(8),
newfs(8)
BUGS
An equivalent facility should be available which operates under a running UNIX
system.
It should be possible to reformat or verify part or all of a disk, then update
the existing bad sector table.