No - PAV would not really help you in a DASD sharing environment. If you
are seeing high device contention for a shared /usr volume you could
create multiple volumes to spread that load across if you're using
dedicated volumes.
MDC on a fullpack ( or 1-end mini) could also help here by avoiding the
I/O altogether.
I have not seen an environment where a shared ro /usr gets that much
activity though. Is this preventative planning or a problem in your
current environment?
Jay Brenneman
James Melin <[EMAIL PROTECTED]>
Sent by: Linux on 390 Port <LINUX-390@VM.MARIST.EDU>
06/04/2005 10:26
Please respond to
Linux on 390 Port
To
LINUX-390@VM.MARIST.EDU
cc
Subject
Re: Latest on PAV's?
So LVM integration of PAV devices would not be a good way to do shared
dasd
amongst many guests, such as sharing /usr read only. My understanding is
that Dedicate locks the device to one guest and one guest only. I guess I
should have been clearer that this was my end-goal. Shared dasd using PAV.
I guess that would be a good reason to supply a pav mini-disk requirement
to IBM for VM enhancement.
Robert J
Brenneman
<[EMAIL PROTECTED] To
om> LINUX-390@VM.MARIST.EDU
Sent by: Linux on cc
390 Port
<[EMAIL PROTECTED] Subject
IST.EDU> Re: Latest on PAV's?
04/06/2005 09:18
AM
Please respond to
Linux on 390 Port
<[EMAIL PROTECTED]
IST.EDU>
for example:
Suppose you want to have PAVs to one 3390-9 volume for the /home
directory. There is the one base address ( 3000 ) and three aliases (
30FF, 30FE, 30FD )
In the user directory, dedicate all 4 devices to the linux guest:
DEDICATE 3000 3000
DEDICATE 30FF 30FF
DEDICATE 30FE 30FE
DEDICATE 30FD 30FD
In the linux guest, make sure all the devices come up at boot time by
adding them to the dasd= parameter in zipl.conf ( or whatever the
preferred method is for your distro)
Each device will appear to linux as a seperate entry in /dev so it may end
up looking something like this:
device 3000 is /dev/dasdb
device 30FF is /dev/dasdc
device 30FE is /dev/dasdd
device 30FD is /dev/dasde
If youre using SLES-8, add /dev/dasdb1 as a pv, create a vg, and then a lv
on it, then reboot. The LVM startup will see the other 3 /dev nodes as
extra paths to the same backing device and you can then use the pvpath
command to enable the PAVs.
If youre using RHEL-3 or RHEL-4 create a multipath software raid device on
the 4 /dev nodes. The multipath software raid tool will know how to use 4
/dev nodes to access one device.
If youre using SLES-9, I think EVMS will do multipath for you, but I'd
have to get back to you with exactly how that would work.
When using PAV, VM does nothing for you since you have to dedicate the
devices to the guest. It stays out of the way completely.
Jay Brenneman
Linux Test and Integration Center
T/L: 295 - 7745
Extern: 845 - 435 - 7745
[EMAIL PROTECTED]
James Melin <[EMAIL PROTECTED]>
Sent by: Linux on 390 Port <LINUX-390@VM.MARIST.EDU>
06/04/2005 09:36
Please respond to
Linux on 390 Port
To
LINUX-390@VM.MARIST.EDU
cc
Subject
Re: Latest on PAV's?
I presume then, that if a PAV device is dedicated to a linux guest then
the
LVM of all the PAVS is still what you do from linux? Or does VM
parallelize
the I/O for you, being that it is handling the I/O?
Terry Spaulding
<[EMAIL PROTECTED]
m> To
Sent by: Linux on LINUX-390@VM.MARIST.EDU
390 Port cc
<[EMAIL PROTECTED]
IST.EDU> Subject
Re: Latest on PAV's?
04/05/2005 01:55
PM
Please respond to
Linux on 390 Port
<[EMAIL PROTECTED]
IST.EDU>
Jim, Linux on zSeries running as a guest supports PAV if the dasd device
is
dedicated to Linux. zVM does not provide support for PAV nor for Linux
dasd
setup as VM minidisk.
If you are looking for PAV for zVM system volumes or for minidisk
supporting
Linux then you need to provide a requirement to IBM for PAV support in zVM
and
for VM minidisk.
-----------------------------------------------------
What's the latest support for PAV's for VM? To support
Linux volumes under VM? Our MVS people want to jump
from 3390-3 to 3390-"12" images. No problem for them,
they have PAV's. But we have to share the shark. Our
preference would be to go to 3390-"12" if there is PAV
support, otherwise a smaller device size.
Jim Sibley
-----------------------------------------------------------------------------------------------------------
Regards,
Terry L. Spaulding
IT Specialist
IBM Global Services
Technology Adoption IVT
[EMAIL PROTECTED]
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