PowerPath and Linux LVM

take a look at this document "PowerPath for Linux Installation Guide 5.1 A03"

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thx dynamox
in CLARiiON host integration course EMC mentioned that
EMC pseudo devices are not supported with the LVM.
PowerPath cannot be installed on a host that uses the Sistina LVM to manage the root file
system.


while in this document "PowerPath for Linux Installation Guide 5.1 A03" they told us how to configure PowerPath with Linux LVM
so the questions is
do pseudo device support Linux LVM ,
can i install powerpath where , LVM manage root file system

thx dynamox

you can definitely use pseudo devices with Linux native LVM ..let me ask my system admin about LVM and root file system.

Hi Guys,

One "Gotcha" for using emcpower devices with Linux LVM is to ensure that you setup LVM filters in the lvm.conf file.

For full details see the PP installation guide P48 and also this Primus solution is extremely useful: emc120281

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PowerPath 4.4 and above now support the use of "emcpower" devices (pseudo devices) in Linux LVM (Sistina LVM)(LVM2). Configuring the /etc/lvm/lvm.conf to ignore all native "sd" devices can work to have LVM to only work with PowerPath devices. Without making changes to the filters in the lvm.conf file, LVM will find volume group information with both the native devices and the emcpower devices, thus seeing duplicates. Either the native devices or the power devices should be filtered out for use with LVM.
Root File System Not Mounted on a Logical Volume
-----------------------------------------------------------------

Modify the filters field of the /etc/lvm/lvm.conf file to prevent LVM2 from scanning sd device nodes.


1. Modify the filter field in the /etc/lvm/lvm.conf file. Replace:


filter=["a/.*/"]
with:
filter=["r/sd*/", "a/.*/"]


2. Rebuild the LVM2 cache. Enter:


vgscan -v


3. Verify that the filter field is working correctly. Run the command below and verify that the filtered device nodes are not listed in the command output. Enter:


lvmdiskscan
Root File System Mounted on a Logical Volume


Identify the underlying device(s) for the root/swap logical volume(s) and the /boot devices (if any). Modify the filters field of the /etc/lvm/lvm.conf file to prevent LVM2 from scanning all sd device nodes except for root/swap and /boot device(s).


1. Identify the root/swap logical volume(s) and the /boot devices (if any). Enter:


df -k
or
mount


2. Identify the underlying device(s) for the root/swap logical volume(s). For example, if the root file system is mounted on logical volume /dev/vg01/lv01, enter:


vgdisplay -v /dev/vg01/lv01


3. Modify the filter field in the /etc/lvm/lvm.conf file to prevent LVM2 from scanning all sd device nodes except for root/swap and /boot devices identified in steps 1 and 2. For
example, if the underlying device for the root/swap file system is /dev/sda2 and /boot is mounted on /dev/sda3, set the filter filter field to:


filter=["a/sda[1-9]$/", r/sd*/", "a/.*/"]


Modify the filter as needed using standard shell-scripting regular expressions. For example, to include partitions sda1 to sda9 for LVM2 while filtering out the remaining sd device nodes, set the filter field to filter=["a/sda[1-9]$/", "r/sd*/", "a/.*/"].

4. Rebuild the LVM2 cache. Enter:


vgscan -v


5. Verify that the filter field is working correctly. Run the command below and verify that the sd device nodes containing the root/swap/boot devices identified in steps 1 and 2 are listed
in the command output, and that the filtered device nodes are not listed in the command output. Enter:


lvmdiskscan


6. Recreate the initrd image to reflect the changes to the /etc/lvm/lvm.conf file. Enter:


mkinitrd
-----------------------------------------------------------------

Root File System Mounted on Mirrored Logical Volumes


Identify the underlying device(s) for the root/swap logical volume(s) and the /boot devices (if any). Modify the filters field of the /etc/lvm/lvm.conf file to prevent LVM2 from scanning all sd device nodes except for root/swap and /boot device(s).

1. Identify the root/swap logical volume(s) and the /boot devices
(if any). Enter:

df -k
or
mount


2. Identify the underlying device(s) for the root/swap and mirror logical volume(s). For example, if the root file system is mounted on logical volume /dev/vg01/lv01 and its mirror is mounted on /dev/vg01/lv02, enter:

vgdisplay -v /dev/vg01/lv01
vgdisplay -v /dev/vg01/lv02


3. Modify the filter field in the /etc/lvm/lvm.conf file to prevent LVM2 from scanning all sd device nodes except for root/swap and /boot devices identified in steps 1 and 2. For
example, if the underlying logical device for the root/swap file system is /dev/sda2 and its mirror is /dev/sdb3, set the filter field to:

filter=["a/sda[1-3]$/", "a/sdb[1-3]$/", "r/sd.\*/", "a/.*/"]



Modify the filter as needed using standard shell-scripting regular expressions. For example, to include partitions sda1 to sda9 for LVM2 while filtering out the remaining sd device nodes, set the filter field to filter=["a/sda[1-9]$/", "r/sd*/", "a/.*/"].

4. Rebuild the LVM2 cache. Enter:

vgscan -v


5. Verify that the filter field is working correctly. Run the command below and verify that the sd device nodes containing the root/swap/boot devices identified in steps 1 and 2 are listed
in the command output, and that the filtered device nodes are not listed in the command output. Enter:

lvmdiskscan


6. Recreate the initrd image to reflect the changes to the /etc/lvm/lvm.conf file. Enter:

mkinitrd

-------------------------------------------------------------------
You must modify the /etc/lvm/lvm.conf file to filter out sd device nodes from its internal cache so that LVM2 recognizes a PowerPath pseudo device as the single path to LUN. The following sections describe how to modify /etc/lvm/lvm.conf on a host where the root file system is:

- Not mounted on a logical volume.
- Is mounted on a logical volume.
- Is mounted on mirrored logical volumes.
-----------------------------------------------------------------

On RHEL 4.0, PowerPath 4.4.0 requires LVM2 version 2.01.08-1.0 and above due to Bugzilla #151657.
-----------------------------------------------------------------
Filter syntax has changed for PowerPath 5.0:
If root is NOT on a logical volume:

RHEL5 / RHEL4.4:
filter = [ "r/sd.*/", "r/disk.*/", "a/.*/" ]

RHEL4.3 or lower:
filter=["r/sd.*/", "a/.*/"]

SLES10 SP1, SLES10, SLES9 SP3:
filter = [ "r|/dev/.*/by-path/.*|",
"r|/dev/.*/by-id/.*|",
"r|/dev/.*/by-name/.*|", "r/sd.*/", "a/.*/" ]

If root IS on a logical volume you need to script carefully to ensure that the correct devices are scanned or excluded from LVM support. Please see the PowerPath 5.0 installation guide for details.
-----------------------------------------------------------------
PowerPath 4.4.0 for Linux supports the Sistina LVM2 on the RHEL 4.0 and SLES 9 SP1 platforms. PowerPath supports the creation of logical volumes on PowerPath pseudo devices only.
=================================

thx dynamox
thx conor

Thanks Conor ..there is a chapter in the installation guide that explains that as well.

Hey everyone, been doing this for a while on RH4 boxes but I've just been given a RH 3 system. It needs an LVM upgrade just to see the powerpath devices properly but I'm having a hard time finding how to restrict it to the emcpowerXX devices as you would in lvm2 with the filter options.

Anyone have any ideas? I haven't implemented yet, I have a feeling it will get the emcpowers by default, just because they're alphabetically before the sdX devices. Hate to rely on that though.

does LVM1 even have filters support ?

Where (a url) can i find a powerpath installation guide for linux red hat 5? Not a white paper or marketing babble but a howto published by emc, not intel or dell or lulu but emc, thanks.

When we run mkinitrd what are the arguments for red hat 5? thx again

Hello, in order to solve problem of removing legacy device paths as described in this forum I added this to /etc/lvm/lvm.conf on Oracle Enterprise Linux 5 update 4 server:

filter = [ "a|/dev/emc.*|", "a|/dev/cciss.*|", "a|/dev/vg01.*|", "r/.*/" ]

and ran vgscan -v, lvmdiskscan, and pvscan. Output shows OS is only seeing cciss (local lvm) and emc (remote lvm) devices and .cache reflect this.

When I reboot, I get a lot of bogus error messages. They don't hurt anything but I want to get rid of them.

Ran

  sudo /sbin/mkinitrd -v -f /boot/initrd-2.6.18-164.el5.img  initrd-2.6.18-164.el5

without any change. Has anyone had this problem?

Example from logs of error:

Mar 22 21:59:29 cddtsh08 kernel: end_request: I/O error, dev sdcf, sector 211812312

Mar 22 21:59:29 cddtsh08 kernel: sd 1:0:1:20: Device not ready: <6>: Current: sense key: Not Ready

Mar 22 21:59:29 cddtsh08 kernel:     Add. Sense: Logical unit not ready, manual intervention required

Also multipathd is running on this server; never turned it off.