Host attachment multipathing scripts

This section provides instructions for applying host attachment multipathing scripts.

Before installing the multipathing software SDD, you must install storage unit attachment scripts on the NAS nodes.

Prepare your environment for migration from a MPIO environment to a SDD environment.
1. If you install the host attachment scripts (devices.fcp.disk.ibm.rte) for the first time on the NAS Gateway 500, you must remove the MPIO drivers. To check if the attachment scripts are installed, enter the following command on a command line: lslpp -La | grep 1750
2. Figure 1 displays the situation where MPIO (devices.fcp.disk.ibm.mpio.rte) is installed, and the 1750 host attachment scripts (devices.fcp.disk.ibm.rte, a prerequisite for SDD) is not installed. Both versions will not coexist on the NAS Node. If they both exist, you must unconfigure and remove the MPIO package.
  Figure 1. Example of installed file set
```
</>-->lslpp -La | grep ibm1750
  devices.fcp.disk.ibm.mpio.rte        1.0.0.0   C   F   IBM 1750 Host Attachment
</>-->_
```
Perform these steps to unconfigure MPIO devices and decide which disks to remove:
1. Issue the following command, as a root user, from the command prompt: lsdev -Cc disk.
  Attention: In the following example, the first two disks (16 Bit LVD SCSI Disk Drive) hdisk0 and hdisk1 are the operating system disks (internal SCSI disks) You must not remove them. Be aware that these numbers are only examples and can be different on your system.
2. Use the following command to delete all MPIO disks: rmdev -dl hdiskX -R. This command deletes the disk from the ODM including all child devices. For example, rmdev -dl hdisk2 -R
  Figure 2 shows an environment with only the internal disks. Be aware that the disk numbers on your system can be different.
  Figure 2. Example environment where all MPIO devices removed
```
</>-->lsdev -Cc disk
hdisk0 Available 1S-08-00-8,0 16 Bit LVD SCSI Disk Drive
hdisk1 Available 1S-08-00-9,0 16 Bit LVD SCSI Disk Drive
```
3. Now you can remove the devices.fcp.disk.ibm.mpio.rte file set. Open a command line, as root user, and enter the following command: installp -u devices.fcp.disk.ibm.mpio.rte. This command removes the MPIO file set.
  The NAS node is now prepared for the devices.fcp.disk.ibm.rte installation.
Find the appropriate scripts on a CD that comes with your storage unit. You can ask your storage unit administrator to get the CD or file sets. To download the file sets from the Internet, go to the following Website: http://www-03.ibm.com/servers/storage/support/software/sdd
Follow the link named 1750 host attachment scripts, then select 1750 Host Attachment Script for SDD on AIX. This selection takes you to a Web page where you can select AIX Host Attachment Script under the Download column.
Download the devices.fcp.disk.ibm.rte.tar file from the Web page into the following local directory on your NAS node: /usr/sys/inst.images
Change to this directory by using the cd /usr/sys/inst.images command. Extract the downloaded devices.fcp.disk.ibm.rte.tar file with the tar -xvf devices.fcp.disk.ibm.rte.tar command.
Create a new table of content file (.toc) by entering the following command: inutoc . (this period is part of the command). This file is used later by the installation procedure.
Run the install SMIT menu (with the fastpath) by entering the following command: smitty install_latest. Specify the path (you can use a period (.) because we changed the directory before, or you can specify the full path). Press Esc+4 and select the appropriate input directory. For example, /usr/sys/inst.images <Installation Directory>.
Place the cursor at SOFTWARE and press Esc+4 to list the software to install.
Move the cursor to ibm1750 and press Esc+7 to select the IBM 1750 disk device (the > should appear in front of the ibm1750 software).
Press Enter and the installation begins.
Use the following command to verify that the file set is installed: lslpp -La | grep ibm1750, as shown in Figure 3.
Figure 3. Example of installed host attachment scripts
```
</usr/sys/inst.images>-->lslpp -La | grep ibm1750
  devices.fcp.disk.ibm.rte         32.6.100.18    C    F    IBM 1750 Disk Device
</usr/sys/inst.images>-->_         
```
If the storage unit and SAN is correctly set up and volumes are assigned to the NAS Gateway 500, you might see a listing of disks when you issue the lsdev -Cc disk command. All disks residing on the storage unit should display the following information in the description: hdiskx...... FC2105xxx.

The system disks hdisk0 (and hdisk1, if the system has two internal disks) do not have the 1750 description.

Tip: At this point, it is not advised to configure volume groups, logical volumes, or file systems on storage unit disks. This should be done after SDD is installed. If volume groups are created before, the administrator has to convert the hdisk volume group to a vpath volume group. (see the hd2vp command in the SDD documentation).

If the physical volumes on an SDD volume group physical volumes are mixed with hdisk devices and vpath devices, you must run the dpovgfix utility to fix this problem. Otherwise, SDD does not function properly. Issue the dpovgfix vg_name command to fix this problem.