Iscsi Root; Controlling The Scsi Command Timer And Device Status - Red Hat ENTERPRISE LINUX - ONLINE STORAGE RECONFIGURATION GUIDE BETA Configuration Manual

Red Hat Enterprise Linux
queue I/O based on the settings in
/etc/iscsi/iscsid.conf

7.3. iSCSI Root

When accessing the root partition directly through a iSCSI disk, the iSCSI timers should be set
so that iSCSI layer has several chances to try to reestablish a path/session. In addition,
commands should not be quickly requeued to the SCSI layer. This is the opposite of what
should be done when
To start with, NOP-Outs should be disabled. You can do this by setting both NOP-Out interval
and timeout to zero. To set this, open
node.conn[0].timeo.noop_out_interval = 0
node.conn[0].timeo.noop_out_timeout = 0
In line with this,
replacement_timeout
system to wait a long time for a path/session to reestablish itself. To adjust
replacement_timeout
node.session.timeo.replacement_timeout = [replacement_timeout]
8. Controlling the SCSI Command Timer and Device
Status
The Linux SCSI layer sets a timer on each command. When this timer expires, the SCSI layer
will quiesce the host bus adapter (HBA) and wait for all outstanding commands to either time
out or complete. Afterwards, the SCSI layer will activate the driver's error handler.
When the error handler is triggered, it attempts the following operations in order (until one
successfully executes):
1. Abort the command.
2. Reset the device.
3. Reset the bus.
4. Reset the host.
If all of these operations fail, the device will be set to the
to that device will be failed, until the problem is corrected and the user sets the device to
.
running
12
/etc/multipath.conf
.
is implemented.
dm-multipath
/etc/iscsi/iscsid.conf
should be set to a high number. This will instruct the
, open
/etc/iscsi/iscsid.conf
instead of
and edit as follows:
and edit the following line:
state. When this occurs, all IO
offline