Hi, me: > > Such a message is rarely harmless. Jens: > Well, that's what I thought, but Andy Polyakov commented here: > http://www.mail-archive.com/[email protected]/msg12106.html
Oh indeed. Now i remember. I stepped into that puddle previously. So for now we count it as harmless. It is quite out of suspicion anyway. See below. > smally$ sudo cmp /dev/sr1 /video/oldc_backup.udf ; echo $? > /dev/sr1 /video/oldc_backup.udf differ: byte 8585217, line 20010 > (my command seemed simpler :-) and as effective) I wanted to truncate /dev/sr1 to the exact size just in case all bytes before match the original and trailing trash would cause false alert. > When I read the block from /dev/sr0 what I get back is all-zeroes. The > corresponding block on the udf image is full of non-zero data. > the next 2048-byte block following 8585216 on /dev/sr1 is non-zero. Ouchers. That looks much like a failure of transport or drive. It happens far before any Close Session failure could spoil it directly, and it is hard to imagine how such a final problem should leave 8 MB unaltered and spoil a single block of 2048 bytes. If possible try to find out whether there are more differing blocks in the image. It is a bit astounding that a first altered block at that address disturbed the UDF tree without any error message. Did you check your kernel logs already ? > Spare Area: 65088/65536=99.3% free > Could it be that there was a defect and things were relocated? I don't > really know how the spare area is used. Actually i never saw it doing any good. It should be transparent to the reader in any case. If the drive hands out logical block 4192 then this should be the corrected data which belong to that address. Any physical address change should be hidden from the reader. It seems the Defect Management had reason to exchange some physical blocks. Of course it is suspicious if the media shows altered blocks afterwards. Normally at least the error detection precautions should have indicated a failure. So this could be a failure of the firmware to correctly perform Defect Management. On BD-RE i normally disable it in favor of triple speed and own MD5 checkreading. I have a BD burner and a BD reader drive so that with bulk backups i reach nearly triple throughput by simultaneaously writing and reading. Nevertheless it may also be a failure of transport. Error detection and verifying happens only after the data reached the drive. Well, it would be expensive to make lots of experiments and to compare the outcome. But currently i see not much other opportunity to gain wisdom. My own experience with BD-R and BD-RE tells me that they are quite reliable. At least compared with early DVDs. So if you need that backup then first try single layer media. It should be not too cumbersome to split 37 GB onto 22.5 GB media. (I could provide my splitting backup program scdbackup, though.) Any problem with the bus should show up with BD-RE as much as with BD-R or BD-R DL. > BTW Thomas thanks for the info about xorisso! Google says "Did you mean: xorriso". That makes me proud. It's now famous enough to be a proposal in the spelling check. In the beginning, google proposed "sorriso" instead. xorriso = X/Open on Rock Ridge enhanced ISO 9660. Have a nice day :) Thomas -- To UNSUBSCRIBE, email to [email protected] with a subject of "unsubscribe". Trouble? Contact [email protected]
