On 12.04.2017 20:54, juha.vu...@pp2.inet.fi wrote:
Trying to add fba mdisk from EDEVICE to sles12.2 guest, and dasd_fba driver
does not create the full partition node, /dev/dasdh1, for it for some reason:
zlnx030:~ # vmcp link '*' 305 a305 mr
zlnx030:~ # chccwdev -e a305
Setting device 0.0.a305 online
Done
zlnx030:~ # lsdasd a305
Bus-ID Status Name Device Type BlkSz Size Blocks
==============================================================================
0.0.a305 active dasdh 94:28 FBA 512 10240MB 20971520
zlnx030:~ # ll /dev/dasdh*
brw-rw---- 1 root disk 94, 28 Apr 12 13:04 /dev/dasdh
Log for setting online:
2017-04-12T13:04:07.613846+03:00 zlnx030 kernel: dasd-fba.f36f2f: 0.0.a305: New
FBA DASD 9336/10 (CU 6310/80) with 10240 MB and 512 B/blk
but not partition creation happening as in SLES11.4 for the same mdisk:
kernel: dasdk:(nonl) dasdk1
Seems that this is related to what old garbage you have in the blocks of the
new mdisk.
Once I dd'd /dev/zero to /dev/dasdh, put it offline and back online, dasd_fba
did its magic and created the partition /dev/dasdh1.
Seems that the logic in dasd drivers for recognizing the type of a dasd is not
inclusive, and the latest level drivers in sles11.4 do better job in that than
the ones in sles12.2.
A bit annoying, but once you know it you can live with it :)
I don't see a point in opening a bug report, now. (Or better, just call me
lazy.)
--
Regards,
Juha
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Hi,
you are right, garbage on the disk might lead to other partition
detection code to take it and it _never_ gets to the DASD specific
partition detection.
You have to mention that the partition detection process is -
independent of the disk type - a hierarchical process. Those partition
detection parts high in the hierarchy are asked first if they would like
to try and possibly take the disk as theirs. Only if they deny or fail
in a proper way the disk gets passed to the next layer. The DASD
specific part is very low in the hierarchy (which is OK since it is
quite uncommon for none s390 systems to have a DASD device). But this
leads to the point that most of the other partition tables overrule the
DASD part. If there is for example a msdos style partition table that
states you have an empty disk without a partition on the FBA DASD, than
the DASD partition detection will never be asked and there will be no
default partition.
So you always have to take care if you recycle previously used disks.
I am not sure why there is this difference between SLES11 and SLES12,
maybe the corresponding partition detection code for the garbage was not
present in SLES11 and now is on SLES12 or whatsoever.
Regards,
Stefan
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