Emulex LightPulse LPe1105-M4 HBA Installation Guide download pdf (Page 159)

Linux device-naming convention

159

Additional Notes

Therefore, if you have allocated LUNs from 0 through 255 to the SLES

8 Linux host, the host can scan and use all 256 logical units. However,

just as with Red Hat distributions, if you present logical units over

256 to a Linux host, the host will neither see nor be able to access

those devices with an address of over 256.

PowerPath examples

When EMC PowerPath

is installed, keep in mind that there is a lim-

itation of 128 SCSI devices total per system, not per adapter.

◆ Example without PowerPath — If you have two HBAs or a dual

channel HBA and you want both ports/HBAs to see and access

devices; you must split the 128 devices between the two HBAs.

For example, 64 devices would be allocated to each HBA. If you

allocate 128 devices to the first HBA, the second HBA will not be

able to access any devices. The limitation of 128 SCSI devices is in

the Linux SCSI subsystem and is per system, not per adapter.

◆ Example with PowerPath — Keep in mind that if you present 128

LUNs to a Linux host to one HBA, then only that one HBA will be

able to see and access devices.

In the case of PowerPath, if you have eight HBAs in a server and

plan to have two paths per HBA, you will be left with only eight

devices per HBA:

128 LUNs/ (8 HBAs * 2 paths) = 8 devices

Character device file names

The corresponding character device file names take the following

form:

/dev/sg

where

begins with zero and increments by one.

The use of the alphabetic sg device file names

/dev/sg[a-d][a-z]

are now deprecated and are used as links to the sg numeric device

filenames.

Current versions of the Solutions Enabler and the included inquiry

utility require the existence of the deprecated alphabetic SCSI generic

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Emulex LightPulse LPe1105-M4 HBA Installation Guide Page 159