Date: Wed, 31 Mar 1999 21:33:59 +1000 (EST) From: Darren Reed <avalon@coombs.anu.edu.au> To: mladavac@metropolitan.at (Ladavac Marino) Cc: dillon@apollo.backplane.com, rb@gid.co.uk, avalon@coombs.anu.edu.au, wilko@yedi.iaf.nl, jkh@zippy.cdrom.com, hackers@FreeBSD.ORG Subject: Re: another ufs panic.. Message-ID: <199903311133.VAA10193@cheops.anu.edu.au> In-Reply-To: <97A8CA5BF490D211A94F0000F6C2E55D097576@s-lmh-wi-900.corpnet.at> from "Ladavac Marino" at Mar 30, 99 10:45:32 am
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In some mail from Ladavac Marino, sie said: [...] > Darren, this could possibly be your problem as well since you > seem to have a lot of hardware hanging off the same power > supply--prehaps it just cannot regulate any more. You could test that > by writing a known pattern to the raw device and then reading it > back--just make sure that the tar runs on EIDE drive writing into the > bit-bucket so that the EIDE does not spin down and that it keeps > seeking--both actions take a lot of power. Well.... first run, no tar on EIDE drive (just two drives now, EIDE & SCSI, nothing else powered, which has ended up with corrupt dirs): gawaine /usr# dd if=/dev/zero bs=16384k of=/dev/rsd0s4 dd: /dev/rsd0s4: short write on character device dd: /dev/rsd0s4: end of device 125+0 records in 124+1 records out 2089221120 bytes transferred in 248.516462 secs (8406772 bytes/sec) Now the interesting part! I wrote my own program to read it back and check that all that was read was indeed null bytes...however! From 874627584 (0x3421c200 - 0x3421cfff) was non-null (actually garbage, not just 0x01 or 0x02 or 0xf0, etc). About 3572 bytes worth. Wanting to confirm the location, I ran it again...this time 95573 bytes. To check disk contents I adapted the program I used to read back to seek to the above position. No problem. A run after that again, 85212 and 33157. Try again with 2.2.8-STABLE (built from GENERIC): # dd if=/dev/zero bs=16384k of=/dev/rsd0s4 dd: /dev/rsd0s4: short write on character device dd: /dev/rsd0s4: end of device 125+0 records in 124+1 records out 2089221120 bytes transferred in 244.473397 secs (8545801 bytes/sec) No non-zero bytes were read back using the program I wrote. And with: # dd if=/dev/rsd0s4 bs=16384k | hexdump -x -n 2089221120 0000000 0000 0000 0000 0000 0000 0000 0000 0000 * 124+1 records in 124+1 records out 2089221120 bytes transferred in 433.489148 secs (4819547 bytes/sec) 7c86fc00 (repeated twice) At no time during this was the hardware changed (though it's in a somewhat state of advaced disarray). Darren To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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