Greetings: I have been using and experimenting with LVM on linux with a product from my employer. I have had excellent results on a few different systems, but am having difficulty with one now that is prompting me to post looking for help and guidance. At the moment, I am using the LVM 1.1rc2 code, having upgraded from the 1.0.4 code when it was failing. The reason I went to the 1.1rc2 code was this is an SMP system and I noticed SMP related fixes mentioned in the changelog. The hardware setup is an IBM x232 server with two 1.3Mhz cpus. No raid adapter. Four scsi drives on the scsi bus. I took the last two drives, one 75G and one 36G, put one large partition on each over all the space and set the partition type to '8e'x. I then created two different volume groups, one each containing each of those two drives. (Yes, I know about all of the many other ways that I could define it multiple drives in one group. I did it this way for a reason.) I then created a set of logical volumes 2.8G in size on each of the two volume groups. The Linux setup is a Redhat 2.4.17 kernel. I have used this same kernel tree on a few other systems with LVM and our product with no difficulty. We need to use raw i/o with our product as can concurrently do tons of I/O to up to 255 slices (or logical volumes using LVM) and we use raw i/o on the other unix platforms. Using the Suse whitepaper's suggestion, I automated one of our boot time startup scripts to create a set of /dev/raw devices with my preferred names and issue the raw command to associate the raw devices to the logical volumes. Since Redhat already has a /dev/raw/raw1 thru /dev/raw/raw128, I decided to create mine starting with minor 129. This all appears to work well as I end up with (one example) crw-rw---- 1 myowner mygroup 162, 129 Jun 26 10:36 33903c0 and raw -q /dev/raw/33903c0 /dev/raw/raw129: bound to major 58, minor 16 and in /var/log/messages I see the timestamped messages like this: /dev/raw/raw129:^Ibound to major 58, minor 16 I can use one of our utilities to prepare (format) the logical volume for use by our product by specifying "/dev/raw/33903c0" with no difficulty and similarly for all of the other logical volume names via their respective /dev/raw specification. Our product also seems to run ok with all of the /dev/raw/xxx devices, too. Here comes the problem description. Two of our other utilties which will backup (read from) or restore (write to) data to the /dev/raw devices cause Linux to hang (must reset or power off to recover). I have tried to do an strace of them, but it hangs the system before any trace data has been written. In an attempt to see if dd caused the same problem, I used another system (laptop) with LVM and our product and strace'd our utility to see what blocksize it was using for reads from the raw device. I then straced a dd bs=875520 if=/dev/raw/33903c0 of=/dev/null. I ctrl-c killed it after about 200 records. I was just starting to look at that trace file using vi when the system hung again! This helps shine the light off of our utilities (I think), though I also see that dd is not supposed to be used against raw devices in the man pages. The author of our utility is well aware of the need to align the buffers, and the same code does work on other raw devices on other LVM linux systems I have put together. I need suggestions for debugging and/or other help to figure out what is going on with this system. -- Gary Eheman Fundamental Software, Inc. http://www.funsoft.com _______________________________________________ linux-lvm mailing list linux-lvm@sistina.com http://lists.sistina.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://www.sistina.com/lvm/Pages/howto.html
