On 25.04.2018 05:48, Donald Russell wrote:
I have a RHEL 7 zLinux on a single Mod-9 ECKD DASD. there are three
partitions:
1 - /boot
2 - swap
3 - /
From one Linux system I tried attaching a not-in-use zLinux Mod-9 and a
Mod-27 and using fdasd and dd to copy the partitions. That didn’t work,
then I tried a VM DDR of the Mod-9 to Mod-27. My thinking was I could then
simply expand the the third partition and expand the file system on it.
When I went to delete/create a new partition fdasd thinks my Mod-27 is
still a Mod-9 (10016 cyls)
I’m guessing there’s something in cyl 0 that tells zLinux the size of the
disk. If I can tweak that to show the disk is actually 32759 cylinders
then I may have a shot at success.
Does anybody have any suggestions for how to move RHEL system from Mod-9 to
Mod-27?
Thanks,
Donald Russell
Hi,
Expanding a CDL formatted ECKD DASD is unfortunately not that easy.(I
assume it is CDL formatted...)
First of all it is important to have the new disk formatted properly in
the same way that the old disk is formatted - using dasdfmt.
It is recommended to format the new DASD _BEFORE_ you try to copy any data.
(Side node: On RHEL7.4 there should be the possibility to format the
remaining part of the dasd using dasdfmt's expand mode: "dasdfmt -M
expand /dev/dasdX". But not sure if it is available on your system.)
Afterwards you should (in theory) use fdasd to re-create the VTOC on the
disk with the new size. fdasd command "u - re-create VTOC re-using
existing partition sizes". And afterwards you could delete the last
partition and re-create it with a bigger size.
But unfortunately (as I tried this recently) there seems to be a bug in
fdasd leading to a message like "BUG: specified free space extent for
deleting not found in FMT5 DSCB!" or something similar with a FMT7 DSCB.
This does not allow you to create a new partition.
The only way I managed to get around this is the following:
- format the new DASD using dasdfmt
- dd old DASD to new DASD
- run blockdev --flushbufs on new DASD to make sure caches are cleared
- write down current partition boundaries
- run fdasd -a on new DASD to create one single partition and fix the size
- run fdasd on the new DASD to
- delete the one partition
- create the three partitions with their old boundaries except the
last one, which can be enhanced to the end of the disk
- run tool to resize the filesystem (usually resize2fs)
This worked for me but you have to be careful with the partition
boundaries as any mistake could lead to a damage of the data.
Regards,
Stefan
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