Dell Emulex Family of Adapters - Manual (Page 964)

Emulex Drivers Version 10.2 for Linux User Manual P010081-01A Rev. A
Appendix A. iSCSI Driver
964
Configuring the iSCSI Driver Parameters
Configuring the ETO and LDTO Parameters
ETO and LDTO values are configurable during insmod time. The ETO value specified
during insmod is the default ETO value that is applied to all targets.
The following example configures the LDTO and ETO during insmod of the driver.
These settings must be used every time the iSCSI driver is loaded by insmod.
insmod be2iscsi.ko ldto=25 eto=20
To pass module parameters to the iSCSI driver when it is being used as a boot
controller, edit the file or the /etc/modprobe.conf file. For example, add the following
line:
options be2iscsi ldto=25 eto=20
Then type
# mkinitrd
The change takes effect the next time the system is booted.
For information on these parameters in relation to SCSI error handling, see “Error
Handling using ETO and LDTO Parameters” on page 966.
Configuring the large_io Parameter
The large I/O (large_io) parameter specifies the maximum transfer size in a single SCSI
command of 128 or 512 KB.
By default, large_io=128, which means the iSCSI driver supports up to 128 KB and 32
scatter gather entries in a single SCSI command. If applications issue I/O requests that
are larger than 128 KB or need more than 32 scatter gather entries, the request is split
into multiple requests by the driver.
When large_io=512, the iSCSI driver can support up to 512 KB of data and a total of 128
scatter gather entries in a single SCSI command. In this case, the iSCSI driver supports a
larger maximum transfer size, but also consumes a larger amount of physical memory.
Intermediate sizes between 64 and 512 KB are accepted, but the memory used by the
driver is the same as for a value of 512. If applications issue I/O requests that are larger
than 512 KB or need more than 128 scatter gather entries, the request is split into
multiple requests by the driver.
Manually Setting the large_io Parameter
To manually set the large_io parameter, type
insmod be2iscsi.ko large_io=512
Permanently Setting the large_io Parameter
To permanently set large_io on every iSCSI boot, edit the /etc/modprobe.conf file. In
the following example, note that the lines beginning with “alias” are added
automatically when the driver is installed. The lines beginning with “options” need to
be added manually for non-default parameters, such as large_io.