User guide

DataDirect Networks SFA™ OS 2.1.1.2 Release Notes Revision A2 | 10
• On SFA10K-E and SFA12K-20E, the CD-DVD_DEVICE attribute must be cleared after
completing an installation and before restarting the stack. (DE7427)
• On SFA12K-20E and SFA10K-E, VMs can be shown as running when a controller
hosting those VMs goes down.
(DE4409)
In certain situations, if one controller in a couplet goes down, the remaining
controller may show the VMs on the offline controller as running. This problem has
been fixed.
5.4 SFA12K and SFA10K
• When an SFA is upgraded from SFA OS v1.5.3 to v2.1.1.2, initiators running RHEL 5.x
may get I/O errors. These errors can occur during a small window of time (typically
less than 5 seconds) when the controller running v1.5.3 is preparing to reboot and
responds ‘Ready’ to a Test Unit Ready inquiry from the initiator. If the host
application re-issues the I/O, I/O will continue as normal.
• To improve failover time with RHEL 6.x and Qlogic cards, the following is
recommended to enable the QLogic driver to react quickly to a loss of path :
Qlogic driver: 8.04.00.06.06.0-k
Add the parameter ‘ql2xasynctmfenable=1’ to /etc/modprobe.d/modprobe.conf
Example line in modprobe.conf:
options qla2xxx ql2xfwloadbin=1 ql2xqfullrampup=15 ql2xasynctmfenable=1
• To improve failover time and to prevent I/O errors, the following settings in
multipath.conf are recommended:
(These settings can be changed for the defaults section which will apply to all
devices, or just under the SFA devices):
checker_timeout 5
dev_loss_tmo 10
fast_io_fail_tmo 5
These settings are included in the DDN multipath package version 1.5-5 and above.
• When the controller is preparing to shutdown, it will first put all its pools into write-
through mode and attempt to flush all the dirty cache. On SFA platforms with
multiple RAID processors (RP), in the case where one RP finishes flushing its cache
before the other RP, the first RP to finish flushing its cache will not service I/O from
the host until the SFA reboots. This may cause I/O errors on the host and cause
applications on the hosts to hang and eventually time out. To work around this issue,
reduce I/O load during planned maintenance activities such as firmware upgrades
and reboots of the controllers so that the flush activities will complete quickly.