[linux-lvm] URGENT!!!!!!problem with behaviour of lvm on Suse

[Sandhya Suman]

Hi,
We are facing some problem related to lvm on SuseLinux
8(Kernel -2.4.19-4GB).
We are trying to port HDLM driver on suse.HDLM driver create psudo driver on
top of scsi driver it uses scsi disk to read and write data.
suppose i have a hdlm device /dev/sddlmaa which is configured for 4 scsi
devices i.e can access the storage device through 4 scsi disk.

Following output shows the link between the scsi and HDLM device.

linux:/opt/DynamicLinkManager/bin # ./dlnkmgr view -drv | grep sddlmaa
000000 sddlmaa          /dev/sda
000008 sddlmaa          /dev/sdi
000009 sddlmaa          /dev/sdq
000010 sddlmaa          /dev/sdy

Now here is the sequence of commands and there outputs to create a volume
group........

linux:/opt/DynamicLinkManager/bin # pvcreate /dev/sddlmaa1 /dev/sddlmaa2
pvcreate -- physical volume "/dev/sddlmaa1" successfully created
pvcreate -- physical volume "/dev/sddlmaa2" successfully created

linux:/opt/DynamicLinkManager/bin # pvscan
pvscan -- reading all physical volumes (this may take a while...)
pvscan -- inactive PV "/dev/sdq1" is in no VG  [30.98 MB]
pvscan -- inactive PV "/dev/sdq2" is in no VG  [69 MB]
pvscan -- inactive PV "/dev/sdt"  is in no VG  [100 MB]
pvscan -- total: 3 [199.98 MB] / in use: 0 [0] / in no VG: 3 [199.98 MB]

Here even if i am creating a PV using HDLM device i.e /dev/sddlmaa1 PVSCAN
shows the corresponding scsi device which it picks from the
/proc/partition.(what i feel is that it picks thescsi disk with highest
major number as scsi are displayed in descending order by their major
numbers in /proc/partition).

linux:/opt/DynamicLinkManager/bin # vgcreate myvg1 /dev/sddlmaa1
/dev/sddlmaa2
vgcreate -- INFO: using default physical extent size 4 MB
vgcreate -- INFO: maximum logical volume size is 255.99 Gigabyte
vgcreate -- doing automatic backup of volume group "myvg1"
vgcreate -- volume group "myvg1" successfully created and activated

linux:/opt/DynamicLinkManager/bin # pvscan
pvscan -- reading all physical volumes (this may take a while...)
pvscan -- ACTIVE   PV "/dev/sdq1" of VG "myvg1" [24 MB / 24 MB free]
pvscan -- ACTIVE   PV "/dev/sdq2" of VG "myvg1" [64 MB / 64 MB free]
pvscan -- inactive PV "/dev/sdt"  is in no VG  [100 MB]

Here again i am trying to create the VG using the same HDLM device i.e
/dev/sddlmaa1 and 2 but again PVSCAN displays the entry for SCSI device.
I had already installed and worked with LVM on RHLinux 7.2 and AS2.1.
There it was working fine The PVSCAN use to show 8 entries for PV create
with 2 partitions of HDLM device.like in the above case.
These 10 entries are comprises of
2 entries for sddlma
2 entries for sda
2 entries for sdi
2 entries for sdq
2 entries for sdy

But in Suse its entirely different. I was trying to track the difference by
looking pvscan -d (debug option).i was also trying to look the code.
What i found that in PVSCAN when it read entries from /proc/partitions one
by one. it compares the UUID and at whenever it finds a match it initializes
some default path and and increment the default path.
In our case i.e  whenever it find hdlm device for which pv is created it
changes the name of the device wuith corresponding scsi device whose UUID is
same...(am i right..)
and from this point it stop recognizing our HDLM device and recognize only
one scsi corresponding to the HDLM device.
and this is the problem.
Can you suggest some solution or some patches which we can apply and get the
behaviour as it shows on RHLinux 7.2.
We have to support load balancing using different paths while using lvm side
by side........
we need ur help very urgetly.............

Thank You,
Sandhya Suman
SE,Patni Computer System
Mumbai,INDIA