Red Hat Linux configuration and attachment

Storage system configuration for Red Hat Linux operations

The storage system must be fully configured before being attached to the Red Hat Linux host, as described in Configuring the storage system.

Host mode
The required host mode for Red Hat Linux is 00. Do not select a host mode other than 00 for Red Hat Linux. For a complete list of host modes for the storage system, see Host modes and host mode options. For instructions on setting the host modes, see the Provisioning Guide for the storage system.
Host mode options
You may also need to set host mode options (HMOs) to meet your operational requirements. For a complete list of HMOs for the storage system, see Host modes and host mode options. For instructions on setting the HMOs, see the Provisioning Guide for the storage system.

Veritas Cluster Server: See Note on using Veritas Cluster Server for important information about using Veritas Cluster Server.

Device Mapper (DM) Multipath configuration for Red Hat Linux

The storage systems support DM Multipath operations for Red Hat Enterprise Linux (RHEL) version 5.4 X64 or X32 or later.

Note Refer to the native multipath configuration documentation from the OS vendor for important information about required settings and parameters for DM Multipath operations, including but not limited to:

Disabling the HBA failover function
Installing the kpartx utility
Creating the multipath device with the multipath command
Editing the /etc/modprobe.conf file
Editing the /etc/multipath.conf file
Configuring LVM
Configuring raw devices
Creating partitions with DM Multipath

NoteSpecify 10 or more values for the no_path_retry parameter in the /etc/multipath.conf file when you use Device Mapper Multipath on RHEL8.

After you specify the parameter, execute the following command to enable the setting:

# systemctl reload multipathd.service

Example of /etc/multipath.conf:

If the setting applies to all devices, add the no_path_retry parameter to defaults.

defaults {
        no_path_retry          10
        find_multipaths yes
        user_friendly_names    yes
}

If the setting applies to each device, add the no_path_retry parameter to device.

devices {
        device {
                vendor "HITACHI"
                product "^OPEN-"
                path_grouping_policy "multibus"
                no_path_retry 10
        }
}

If the no_path_retry parameter is not specified, server I/O or the system that booted from SAN might be stopped when failure is detected on the storage controllers.

Verifying new device recognition for Red Hat Linux

The final step before configuring the new disk devices is to verify that the host system recognizes the new devices. The host system automatically creates a device file for each new device recognized.

Procedure

Use the dmesg command to display the devices.

# dmesg | more
:
:
scsi0 : Qlogic QLA2200 PCI to Fibre Channel Host Adapter: 0 device 14 irq 11
       Firmware version:  1.17.26, Driver version  2.11 Beta
                                                                   
scsi : 1 host.
  Vendor: HITACHI        Model: OPEN-3            Rev: 0111
  Type:   Direct-Access                      ANSI SCSI revision: 02
Detected scsi disk sda at scsi0, channel 0, id 0, lun 0
            

  Vendor: HITACHI        Model: OPEN-9            Rev: 0111
  Type:   Direct-Access                      ANSI SCSI revision: 02
Detected scsi disk sdb at scsi0, channel 0, id 0, lun 1
:
:

In this example, the HITACHI OPEN-3 device (TID 0, LUN 0) and the HITACHI OPEN-9 device (TID 0, LUN 1) are recognized by the Red Hat Linux server.

Record the device file name for each new device. You will need this information when you partition the devices. The following figure shows a sample SCSI path worksheet.

LDEV (CU:LDEV)	Device Type	LUSE ( *n)	VLL (MB)	Device File Name	Path	Alternate Path
0:00					TID:____ LUN:____	TID:____ LUN:____
0:01					TID:____ LUN:____	TID:____ LUN:____
0:02					TID:____ LUN:____	TID:____ LUN:____
0:03					TID:____ LUN:____	TID:____ LUN:____
0:04					TID:____ LUN:____	TID:____ LUN:____
0:05					TID:____ LUN:____	TID:____ LUN:____
0:06					TID:____ LUN:____	TID:____ LUN:____
0:07					TID:____ LUN:____	TID:____ LUN:____
0:08					TID:____ LUN:____	TID:____ LUN:____
0:09					TID:____ LUN:____	TID:____ LUN:____
0:0A					TID:____ LUN:____	TID:____ LUN:____
0:0B					TID:____ LUN:____	TID:____ LUN:____
0:0C					TID:____ LUN:____	TID:____ LUN:____
0:0D					TID:____ LUN:____	TID:____ LUN:____
0:0E					TID:____ LUN:____	TID:____ LUN:____
0:0F					TID:____ LUN:____	TID:____ LUN:____

The device files are created under the /dev directory. Verify that a device file was created for each new disk device.
```
# ls -l /dev | more
:
brw-rw----   1 root    disk    8,  0 May  6  1998 sda  
```
In this example, the device file is sda.

Configuring the new devices on Red Hat Linux

This section describes how to configure the new disk devices on the Red Hat Linux system host.

Setting the number of logical units for Red Hat Linux

Use this procedure to set the number of logical units (LUs).

Procedure

Edit the /etc/modules.conf file to add the following line:
options scsi_mod max_scsi_luns=xx
where xx is the maximum number of LUs supported by your Linux OS. Check your host adapter documentation and Linux system documentation to determine the total number of devices that can be supported.
To set the Emulex Driver, add the following line to the /etc/modules.conf file:
```
Alias scsi_hostadapter lpfcdd
```
To activate the above modification, make an image file for booting. Example:
```
# mkinitrd /boot/initrd-2.4.x.scsiluns.img 'uname -r'
```
Use one of the following methods to change the setting of Bootloader:
- When LILO is used as Bootloader: Edit the lilo.conf file, and then issue the lilo command to activate the lilo.conf setting with selecting the label. Example:
```
image=/boot/vmlinuz-qla2x00
       label=Linux-qla2x00
       append=“max_scsi_luns=16”
       # initrd=/boot/initrd-2.4.x.img                     
       initrd=/boot/initrd-2.4.x.scsiluns.img                       
 root=/dev/sda7
 read-only
#sbin/lilo
```
  As shown in this example, the initrd=/boot/initrd-2.4.x.img line is commented out, and the initrd=/boot/initrd-2.4.x.scsiluns.img line is added.
- When Grand Unified Bootloader (GRUB) is used as Bootloader: Edit the /boot/grub/grub.conf file. Example:
```
kernel /boot/vmlinuz-2.4.x ro root=/dev/hda1
# initrd /boot/initrd-2.4.x.img　                            
initrd /boot/initrd-2.4.x.scsiluns.img   
```
Reboot the system.

Partitioning the new disk devices for Red Hat Linux

After the setting the number of logical units, you need to create the partitions on the new disk devices.

NoteFor important information about required settings and parameters for DM Multipath operations, refer to the native multipath configuration documentation from the OS vendor.

Procedure

Enter fdisk/dev/<device_name>, for example:
```
fdisk/dev/sda
```
where
- dev/sda is the device file name.
Select p to display the present partitions.
Select n to make a new partition. You can make up to four primary partitions (1-4) or one extended partition. The extended partition can be organized into 11 logical partitions, which can be assigned partition numbers from 5 to 15.

TipOther useful commands include d to remove partitions and q to stop a change.
Select w to write the partition information to disk and complete the fdisk command.
Repeat steps 1 through 4 for each new disk device.

Creating, mounting, and verifying the file systems on Red Hat Linux

Creating the file systems for Red Hat Linux

After you have partitioned the disk devices, you need to create the file system. Be sure the file system is appropriate for the primary and/or extended partition for each logical unit.

Procedure

Issue the mkfs command, for example:
```
# mkfs /dev/sda1
```
where
- /dev/sda1 is device file of primary partition number 1.

Creating the mount directories for Red Hat Linux

Issue the mkdir command, for example:
```
# mkdir /VSP-LU00
```

Mounting the new file systems for Red Hat Linux

Use the mount command to mount each new file system, for example:
```
# mount /dev/sda1 /VSP-LU00
```
The first parameter of the mount command is the device file name (/dev/sda1), and the second parameter is the mount directory (VSP-LU00).

Verifying the file systems for Red Hat Linux

After mounting the file systems, you need to verify the file systems, for example:

Procedure

Issue the df -h command.

# df -h
Filesystem           Size     Used    Avail    Used%    Mounted on
/dev/sda1            1.8G     890M     866M     51%      /
/dev/sdb1            1.9G     1.0G     803M     57%      /usr
/dev/sdc1            2.2G      13k     2.1G      0%      /VSP-LU00
#

Setting the auto-mount parameters for Red Hat Linux

Make a backup of the /etc/fstab file, for example:
```
# cp -ip /etc/fstab /etc/fstab.standard 
```

Edit the /etc/fstab file to add the new devices, for example:

# vi /etc/fstab                                                    
:
/dev/sda1         /VSP-LU00 ext2    defaults   0   2

Troubleshooting for Red Hat Linux host attachment

The following table lists potential error conditions that might occur during storage system installation on a Red Hat Linux host and provides instructions for resolving the conditions. If you cannot resolve an error condition, contact customer support.

Error Condition	Recommended Action
The logical devices are not recognized by the system.	Be sure that the READY indicator lights on the storage system are ON. Be sure that the LUNs are properly configured. The LUNs for each target ID must start at 0 and continue sequentially without skipping any numbers.
The file system cannot be created.	Be sure that the device name is entered correctly with mkfs. Be sure that the LU is properly connected and partitioned.
The file system is not mounted after rebooting.	Be sure that the system was restarted properly. Be sure that the auto-mount information in the /etc/fstab file is correct.

Quick Links

Storage system configuration for Red Hat Linux operations

Device Mapper (DM) Multipath configuration for Red Hat Linux

Verifying new device recognition for Red Hat Linux

Configuring the new devices on Red Hat Linux

Setting the number of logical units for Red Hat Linux

Partitioning the new disk devices for Red Hat Linux

Creating, mounting, and verifying the file systems on Red Hat Linux

Creating the file systems for Red Hat Linux

Creating the mount directories for Red Hat Linux

Mounting the new file systems for Red Hat Linux

Verifying the file systems for Red Hat Linux

Setting the auto-mount parameters for Red Hat Linux

Troubleshooting for Red Hat Linux host attachment