Steps performed

• Power off data server
• Take one drive out of the data server and put it into powered-off compute node
• power on compute node
• choose a LBA which should be "corrupted", e.g. 59511
• save the data around this block:

 dd if=/dev/sdb of=precorruption.data bs=512 skip=59500 count=100

• corrupt data

 make_bad_sector /dev/sdb 59511

• The output should read:

 /dev/sdb: readback test LBA=59511
 /dev/sdb: success
 /dev/sdb: writing LBA=59511
 /dev/sdb: readback test LBA=59511 (this should fail)
 /dev/sdb: readback failed

• check if it worked

 smartctl -data -t long /dev/sdb

• This should fail (after a very short time) with the LBA chosen. The error message at the end of the output of

 smartctl -data -a /dev/sdb

should read:

 # 1 Extended offline Completed: read failure 90% 1339 59511

(of course some numbers will vary for you).

• NOTE: if you happen to have a very recent version of smartmontools (at the time of writing this is a CVS-only feature), try using -d sat to enable you to run a selctive test. This won't take as long.
• now power down compute node
• remount the disk into the data server
• power up the data server
• start scrubbing with (cli64-172 is Areca's command line tool version 1.72):

 ./cli64-172 vsf check vol=1

(if no error is detected and there is another volume, please check this also!)

• to watch the progress:

 watch -n 30 ./cli64-172 vsf info

• and after the check:

 ./cli64-172 event info

This one should read like:

 2008-01-26 16:21:11 IDE Channel # 5 Reading Error

• wait until check is done - it should be found and corrected
• power down the data server
• remount disk into compute node (powered off again)
• power on the compute node
• run dd again to see of the data is still the same
• further check:

 make_bad_sector --readback /dev/sdb 59511

This should not fail.

And it does not fail (also, smartctl does not fail)

Conclusion: Areca 1261ML DOES do a proper job with scrubbing.

ToDo: Length of test

Helper scripts

do_bad.sh with example configuration

 #!/bin/bash
 # configure the script here THINK TWICE
 # Damage sectors between 201GB - 209GB
 LBA_LIST="421528000 421569110 421597920 421629030 421729440 421892850 425342760 429423403 431324854 436924732"
 LBA_FIRST=419430400
 LBA_LAST=440401900
 BYTE_SIZE=512
 HARD_DRIVE=/dev/sdb
 OUT_PRE_FILE=precorruption.data
 # DO NOT TOUCH THE LINES BELOW
 let FILE_SIZE=$LBA_LAST-$LBA_FIRST
 echo Calculated size: $FILE_SIZE
 echo Create $OUT_PRE_FILE
 dd if=$HARD_DRIVE of=$OUT_PRE_FILE bs=$BYTE_SIZE skip=$LBA_FIRST count=$FILE_SIZE
 echo Corrupt drive
 for i in $LBA_LIST; do
 echo make_bad_sector $HARD_DRIVE $i
 done