Cinder LVMiSCSI driver is using default value of write-cache parameter
of tgtd iscsi driver. In this setting, write I/O from guest instance is
cached on dirty cache of a host.(write-back mode)
In this case, data lost may be occurred if the host crashes before
flushing dirty cache. This may cause a lot of instances to lose
their data.
In order to avoid this issue, it is better to turn off the write cache.
(write-through mode)
This patch adds "iscsi_write_cache" parameter to configure a behavior of
write cache. The default value is "iscsi_write_cache=on".(write-back mode)
Reviewed: https:/ /review. openstack. org/104714 /git.openstack. org/cgit/ openstack/ cinder/ commit/ ?id=617e59bde66 0f919df0818611b 911ae35f8b7247
Committed: https:/
Submitter: Jenkins
Branch: master
commit 617e59bde660f91 9df0818611b911a e35f8b7247
Author: Mitsuhiro Tanino <email address hidden>
Date: Tue Jul 8 15:52:11 2014 -0400
Configure write cache option of tgtd iscsi driver
Cinder LVMiSCSI driver is using default value of write-cache parameter
of tgtd iscsi driver. In this setting, write I/O from guest instance is
cached on dirty cache of a host.(write-back mode)
In this case, data lost may be occurred if the host crashes before
flushing dirty cache. This may cause a lot of instances to lose
their data.
In order to avoid this issue, it is better to turn off the write cache.
(write-through mode)
This patch adds "iscsi_write_cache" parameter to configure a behavior of write_cache= on".(write- back mode)
write cache. The default value is "iscsi_
Closes-Bug: 1336568
DocImpact
Change-Id: I7a495bc6118d42 54576bdf1620a04 ac537b3078d
Signed-off-by: Mitsuhiro Tanino <email address hidden>