Linuxers,
Thank you for your time and and any help you can offer. Does
anybody know how to correct an unreliable scsi disk? Has anyone had
similar experience? How was it solved?
In February, I purchased a 9 G SCSI hard disk and Ultra Wide
SCSI 2 controller. I upgraded to linux 2.2 and have found the system
too unreliable for its intended purpose, CDROM generation.
I can duplicate the problem by simply copying a 300K file repeatedly
to fill the partition, and then comparing each copy to the original. When
a bash script is used, ~3 out of ~7500 comparisons fail. When perl is
used, ~6 out of ~7500 comparisons fail.
---- discoveries ----
o If the file copy step is skipped, (the same disk image files
are compared again, the frequency of comparison failures
remains the same, but the specific files that fail differs.
(I believe this implies, that reads during comparison are
failing. I believe this implies that writes during copy
are error-free.)
o Using fdisk(8), I have tried setting the end of partition 4 at
1106 cylinders and at 1023 cylinders. There appears to be
no effect. After writing the partition table, I power
cycled the computer. After recreating the file system
with mke2fs(8), I power cycled the computer.
o badblocks(8) write-mode test found no bad blocks.
o Though not as easily or thoroughly tested, all other partitions
appear to be reliable.
---- discoveries ----
---- duplication algorithm ----
#! /usr/bin/perl
# Set the following to 0 to use the same disk file images.
if (1) {
#
# Clear memory
#
for ($f = 0; $f < 8; $f++) {
system("rm buffer/suspect.$f*");
}
#
# Fill the disk
#
for ($a = 0; $a < 8; $a++) {
for ($b = 0; $b < 10; $b++) {
for ($c = 0; $c < 10; $c++) {
for ($d = 0; $d < 10; $d++) {
system("cp random300K.bin buffer/suspect.$a$b$c$d");
}
}
}
}
}
#
# Verify the copy
#
@bad = ();
for ($a = 0; $a < 6; $a++) {
for ($b = 0; $b < 10; $b++) {
for ($c = 0; $c < 10; $c++) {
for ($d = 0; $d < 10; $d++) {
if ("$a$b$c$d" < 5813) {
if (system("cmp -s random300K.bin buffer/suspect.$a$b$c$d")) {
push @bad, "$a$b$c$d";
print "Bad block: $a$b$c$d\n";
}
}
}
}
}
}
#
# Record the bad blocks
#
$count = scalar(@bad);
system("echo $count >> /mnt/scsi_000p2/tmp/count");
#
# Mark bad blocks
#
foreach $b (@bad) {
local($dev,$ino,$mode,$nlink,$uid,$gid,$rdev,$size,$atime,$mtime,$ctime,$blksize,$blocks)
= stat("buffer/suspect.$b");
print "Renaming buffer/suspect.$b -> /mnt/scsi_000p4/bad_blocks/$ino\n";
rename "buffer/suspect.$b","/mnt/scsi_000p4/bad_blocks/$ino";
}
---- duplication algorithm ----
---- partition table ----
Disk /dev/sda: 255 heads, 63 sectors, 1106 cylinders
Units = cylinders of 16065 * 512 bytes
Device Boot Begin Start End Blocks Id System
/dev/sda1 1 1 368 2955928+ 6 DOS 16-bit >=32M
/dev/sda2 * 369 369 736 2955960 83 Linux native
/dev/sda3 737 737 744 64260 82 Linux swap
/dev/sda4 745 745 1023 2241067+ 83 Linux native
---- partition table ----
---- platform ----
Platform: Dell Dimension XPS 133c
CPU: Pentium 133MHz, 256K cache
OS: linux-2.2.1
scsi0 : Adaptec AHA274x/284x/294x (EISA/VLB/PCI-Fast SCSI) 5.1.10/3.2.4
<Adaptec AHA-294X Ultra2 SCSI host adapter>
scsi1 : SCSI host adapter emulation for IDE ATAPI devices
scsi : 2 hosts.
Vendor: SEAGATE Model: ST39173LW Rev: 6246
Type: Direct-Access ANSI SCSI revision: 02
Detected scsi disk sda at scsi0, channel 0, id 0, lun 0
Vendor: HP Model: CD-Writer+ 8100 Rev: 1.0g
Type: CD-ROM ANSI SCSI revision: 02
---- platform ----
--
Dr. Robert J. Meier
1-248-650-9488
[EMAIL PROTECTED]
