Hi Florian, On Mon, 22 Nov 2010, Florian Bilek wrote: > Dear all > > Since some weeks I am facing some weird problem with SLES 11 SP1. I am on > the current patch level with that image (I hope), the kernel is: > > # uname -a > Linux sles11 2.6.32.24-0.2-default #1 SMP 2010-10-29 16:39:49 +0200 s390x > s390x s390x GNU/Linux > > I use that guest for cloning purposes and because of that I am very often > attaching and detaching MINIDISKS, doing formatting, copying etc. > > 1. problem: > > I link a minidisk from another guest which is surely down via the vmcp link > command and then do a chccwdev -e. > > vmcp link clonset7 201 7201 w > chccwdev -e 0.0.7201 > > I see with lsdasd that this device is active. > > lsdasd > Bus-ID Status Name Device Type BlkSz Size Blocks > ============================================================================== > 0.0.0201 active dasda 94:0 ECKD 4096 7043MB 1803060 > 0.0.0203 active dasdb 94:4 ECKD 4096 7043MB 1803060 > 0.0.0400 active dasdc 94:8 ECKD 4096 892MB 228600 > 0.0.7201 active dasdd 94:12 ECKD 4096 1573MB 402840 > > So far so good. Now I am going to change that device 7201 offline and detach > it from the linux guest. > > lsdasd shows that the device is gone and I also don't have any item in > /sys/bus/ccw/devices > > Next is that I link that device again in r/o mode: > vmcp link clonset7 201 7201 r > chccwdev -e 0.0.7201 > > and lsdasd shows > > # lsdasd > Bus-ID Status Name Device Type BlkSz Size Blocks > ============================================================================== > 0.0.0201 active dasda 94:0 ECKD 4096 7043MB 1803060 > 0.0.0203 active dasdb 94:4 ECKD 4096 7043MB 1803060 > 0.0.0400 active dasdc 94:8 ECKD 4096 892MB 228600 > 0.0.7201 active(ro) dasdd 94:12 ECKD 4096 1573MB 402840 > > which is also still correct. > > Now the problem comes: When I detach again the device and re-link it again > in r/w mode, the flag that the device is r/o still remains. > > I don't know how that comes but when I do a vmcp q v dasd that device is > shown as R/W from CP side. > > I think that might be a bug since I don't see why is behaves like that.
so the sequence is basically: 1) attach r/o 2) set online 3) detach 4) attach r/w short answer: set the device offline prior to detach and back online after attach as r/w then it will be recognized as r/w long answer: When detaching a dasd which is online, linux will not unregister this device to prevent I/O errors (e.g. you could still have a filesystem mounted). Instead the device is set in a special state (you can check this via "lscss --avail") - if you reattach the device it will be recovered from linux and pending I/O requests will be fulfilled. The r/o detection is done by the dasd driver when you set the device online. So after step 4 the device is still handled as r/o by the dasd driver. This works as designed - you should not change the characteristics of a device if it is still used by linux. > > > 2. Problem: > > Because I lack the FLASHCOPY function I use for disk to disk copy dd. > > dd bs=4096 if=/dev/dasdx of=/dev/dasdy > > In principle it works ok. But when I do a chccwdev -d 0.0.xxxx even with an > udevadm settle --timeout=20 afterwards, > the file system gets corrupted, when I attach it to another guest. > > I am really lost since all that was working well under SLES 10 SP2. I would > really like to know if someone had similar experience in SLES 11 SP1. The data is not guaranteed to be written in this case. This is due to changes in the linux block layer (it was not guaranteed to be written in sles 10 either but worked by chance). You have 2 options here: * tell dd to sync its data (check the man page - i think the option is fsync) * manually run "sync" after dd returns regards, Sebastian > > Thank you in advance. > > Kind regards, > > Florian > > ---------------------------------------------------------------------- > For LINUX-390 subscribe / signoff / archive access instructions, > send email to [email protected] 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/ > ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to [email protected] 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/
