| Message ID | f854a325cfc48af3957fc4eae3018b5e@crc.id.au (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Hi Steven On Mon, May 09, 2016 at 02:22:48PM +1000, Steven Haigh wrote: > On 2016-05-05 15:52, Steven Haigh wrote: > >On 2016-05-05 12:32, Steven Haigh wrote: > >>Overview > >> > >>If you're using iSCSI, you can mount a target by multiple Dom0 > >>machines on the same target. For non-cluster aware filesystems, this > >>can lead to disk corruption and general bad times by all. The iSCSI > >>protocol allows the use of persistent reservations as per the SCSI > >>disk spec. Low level SCSI commands for locking are handled by the > >>sg_persist program (bundled with sg3_utils package in EL). > >> > >>The aim of this patch is to create a 'locktarget=y' option specified > >>within the disk 'target' command for iSCSI to lock the target in > >>exclusive mode on VM start with a key generated from the local systems > >>IP, and release this lock on the shutdown of the DomU. > >> > >>Example Config: > >>disk = > >>['script=block-iscsi,vdev=xvda,target=iqn=iqn.1986-03.com.sun:02:mytarget,portal=iscsi.example.com,locktarget=y'] You seem to suggest an extension (locktarget) to disk spec as well but you patch doesn't contain modification to docs/txt/misc/xl-disk-configuration.txt. Wei.
On 2016-05-12 21:02, Wei Liu wrote: > Hi Steven > > On Mon, May 09, 2016 at 02:22:48PM +1000, Steven Haigh wrote: >> On 2016-05-05 15:52, Steven Haigh wrote: >> >On 2016-05-05 12:32, Steven Haigh wrote: >> >>Overview >> >> >> >>If you're using iSCSI, you can mount a target by multiple Dom0 >> >>machines on the same target. For non-cluster aware filesystems, this >> >>can lead to disk corruption and general bad times by all. The iSCSI >> >>protocol allows the use of persistent reservations as per the SCSI >> >>disk spec. Low level SCSI commands for locking are handled by the >> >>sg_persist program (bundled with sg3_utils package in EL). >> >> >> >>The aim of this patch is to create a 'locktarget=y' option specified >> >>within the disk 'target' command for iSCSI to lock the target in >> >>exclusive mode on VM start with a key generated from the local systems >> >>IP, and release this lock on the shutdown of the DomU. >> >> >> >>Example Config: >> >>disk = >> >>['script=block-iscsi,vdev=xvda,target=iqn=iqn.1986-03.com.sun:02:mytarget,portal=iscsi.example.com,locktarget=y'] > > You seem to suggest an extension (locktarget) to disk spec as well but > you patch doesn't contain modification to > docs/txt/misc/xl-disk-configuration.txt. Correct. There is no documentation for the existing block-iscsi script within xl-disk-configuration.txt. In fact, there is no mention at all regarding block-iscsi in any of the documentation that I can see.
--- block-iscsi 2016-05-09 15:16:35.447480532 +1000 +++ block-iscsi-lock 2016-05-05 15:43:58.222159351 +1000 @@ -37,8 +37,7 @@ { # set multipath default value multipath="n" - for param in $(echo "$1" | tr "," "\n") - do + for param in $(echo "$1" | tr "," "\n"); do case $param in iqn=*) iqn=$(remove_label $param "iqn=") @@ -55,6 +54,15 @@ fatal "Multipath selected, but no multipath tools found" fi ;; + locktarget=*) + locktarget=$(remove_label $param "locktarget=") + if ! command -v sg_persist > /dev/null 2>&1; then + fatal "Locking requested but no sg_persist found" + fi + if ! command -v gethostip > /dev/null 2>&1; then + fatal "Locking requested but no gethostip found for key generation" + fi + ;; esac done if [ -z "$iqn" ] || [ -z "$portal" ]; then @@ -92,6 +100,31 @@ fi } + +lock_device() +{ + ## Lock the iSCSI target as Exclusive Access. + key=$(gethostip -x $(uname -n)) + if ! sg_persist -d ${dev} -o -G -S ${key} > /dev/null; then + unlock_device + iscsiadm -m node --targetname "$iqn" -p "$portal" --logout > /dev/null + fatal "iSCSI LOCK: Failed to register with target" + fi + if ! sg_persist -d ${dev} -o -R -K ${key} -T 6 > /dev/null; then + unlock_device + iscsiadm -m node --targetname "$iqn" -p "$portal" --logout > /dev/null + fatal "iSCSI LOCK: Failed to set persistent reservation" + fi +} + +unlock_device() +{ + ## Unlock the iSCSI target. + key=$(gethostip -x $(uname -n)) + sg_persist -d ${dev} -o -L -K ${key} -T 6 > /dev/null || true + sg_persist -d ${dev} -o -G -K ${key} -S 0 > /dev/null || true +} + command=$1 target=$(xenstore-read $XENBUS_PATH/params || true) if [ -z "$target" ]; then @@ -110,10 +143,17 @@ ## Login to the iSCSI target. do_or_die iscsiadm -m node --targetname "$iqn" -p "$portal" --login > /dev/null - + find_device + if [ "$locktarget" = "y" ]; then + lock_device + fi write_dev $dev ;; remove) + find_device + if [ "$locktarget" = "y" ]; then + unlock_device + fi do_or_die iscsiadm -m node --targetname "$iqn" -p "$portal" --logout > /dev/null ;; *)