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6 logical device files for hdlm devices – HP Hitachi Dynamic Link Manager Software User Manual

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2. HDLM Functions

17

2.6 Logical Device Files for HDLM Devices

The logical device file name of an HDLM device is different from the logical device

file name of a SCSI device. When you configure the logical device file of an HDLM

device for applications such as volume management software, these applications can

access the LUs that HDLM manages.
The following shows an example of the logical device file name that the application

uses to access the LU (for accesses before and after HDLM installation).
Table 2-5: Example of Using the Logical Device File Name of the Device Used When

the Application Accesses the LU illustrates the logical device file name of the device
that the application uses, for before and after HDLM installation.

Table 2-5: Example of Using the Logical Device File Name of the Device Used

When the Application Accesses the LU

The logical device file name of an HDLM device has the following format:

/dev/sddlm[

aa-pap

][

1-15

]

About alphabetic letters used in the logical device file name:

For the first 256 LUs, two alphabetic letters are assigned. The specifiable

values for the first two characters are in the range from

a

to

p

.

For the 257th and subsequent LUs, three alphabetic letters are assigned. The

specifiable values for the first and third characters are in the range from

a

to

p

. The value of the second character is always

a

.

A major number is required for each of the first characters.

Figure 2-6: About Alphabetic Letters Used in the Logical Device File Name shows

information about alphabetic letters used in the logical device file name.

Host status

Device file name that the application uses

Before installing HDLM

The application uses the logical device file name for the SCSI device.
Example:

sda

sdb

After installing HDLM

The application uses the logical device file name for the HDLM device.

Example:

sddlmaa

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