> One error message is ignorable. Hundreds are a problem that should be > fixed.
I just had to learn this the hard way... I started playing with raw_track_access, noticed the large number of I/O errors reported, but paid it no mind and made it work. I wrote a CKD track that was not recognized as a known format and I fixed my problem. Then I started to do more large scale testing and found out that while I can write the track to a minidisk on one real device, others would not let me write the track. I have noticed that the vendor (as reported in /sys) of the good device is IBM and the one that I cannot write to is HTC. And again I have a large wall of I/O errors and sense data... I'm on the verge of giving up on trying to drive all this from Linux. We already have a working directory manager user exit that puts a label on every new disk to let Linux know that the disk is not formatted in any known format. That takes care of the problem. The problem is that when Linux puts a disk online, it does analysis of the disk to determine if it is in a known format. If it finds a known format it starts reading all over the disk. If there are errors, like bad cylinders in the count field, all kinds of bad things can happen. There is no way to bring the disk online without doing the analysis, which means that Linux does not have a way to safely format its own disks. If there was a way to tell the kernel to bring the device online without the analysis, the problem would be solved. There is a state called "unformatted" where the disk goes if kernel can't identify a known label. I would like to have a way to explicitly put a disk online in the unformatted state. For example, writing 1 to /sys/bus/ccw/devices/<vaddr>/online would bring the disk online with format detection and writing 2 would put it online without detection, ending up in "unformatted" state. If the user knew that they intend to format a disk with potentially unsafe data on it they could just bring it online unformatted. (By unsafe I mean data that may be partially in a good format and partially in bad). Tomas ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to lists...@vm.marist.edu with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390 ---------------------------------------------------------------------- For more information on Linux on System z, visit http://wiki.linuxvm.org/
