Hi, I may have experienced some odd behavior from ZFS running 8.0-STABLE-201004 amd64.
I have a zpool 'zhome' on my laptop with checksum=on and copies=2. I was getting ready to burn a FreeBSD DVD today and was verifying the checkums of the image I downloaded (stored on zhome). I got a match on the md5 hash, but a mismatch on the sha256 hash. Rerunning the sha256 hash gave the correct result. I luckily just got in the office earlier and had a zpool status in my terminal buffer which indicated no errors on zhome. Running zpool status after the checksumming operations shows one checksum error. I was under the impression that ZFS, upon encountering a checksum error, would check the second copy of the block (since I have set copies=2) and send that data instead (assuming it was correct), that does not seem to have happened. I have run into checksum errors in the past where I had copies=1, in those cases ZFS would simply stop reading the file at that point and I would get a read error, which I did not in this case. Also I am fairly certain that the dvd image was not buffered in RAM between hashes (i.e. each hash read the data from disk). Perhaps the checksum was correct the first time around and some other part of my system corrupted the data? RAM has been tested many months ago using memtest86 and several other tools without problem (not that new problems couldn't have popped up). a...@moony:~$ zpool status zhome pool: zhome state: ONLINE scrub: none requested config: NAME STATE READ WRITE CKSUM zhome ONLINE 0 0 0 ad4p3.eli ONLINE 0 0 0 errors: No known data errors a...@moony:ISOs$ grep *8.0*amd64-dvd1* CHECKSUM.* | cut -d\= -f2 227adf4b4010aa1bc98baf50953ec2d0 4c087a9d23a53f861f3548461cde500a6db709ff704e972c51677531ea6d65b3 a...@moony:ISOs$ md5 FreeBSD-8.0-STABLE-201005-amd64-dvd1.iso | cut -d\= -f2 227adf4b4010aa1bc98baf50953ec2d0 a...@moony:ISOs$ sha256 FreeBSD-8.0-STABLE-201005-amd64-dvd1.iso | cut -d\= -f2 4fcbcaacf14ff7c0394f119b1ca93e645456241d5b7d42aaf8f92b5a70b279d4 a...@moony:ISOs$ sha256 FreeBSD-8.0-STABLE-201005-amd64-dvd1.iso | cut -d\= -f2 4c087a9d23a53f861f3548461cde500a6db709ff704e972c51677531ea6d65b3 a...@moony:ISOs$ zpool status zhome pool: zhome state: ONLINE status: One or more devices has experienced an unrecoverable error. An attempt was made to correct the error. Applications are unaffected. action: Determine if the device needs to be replaced, and clear the errors using 'zpool clear' or replace the device with 'zpool replace'. see: http://www.sun.com/msg/ZFS-8000-9P scrub: none requested config: NAME STATE READ WRITE CKSUM zhome ONLINE 0 0 0 ad4p3.eli ONLINE 0 0 1 errors: No known data errors a...@moony:ISOs$ -akm _______________________________________________ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to "freebsd-questions-unsubscr...@freebsd.org"