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scst/README: Update implicit ALUA section
git-svn-id: http://svn.code.sf.net/p/scst/svn/trunk@5456 d57e44dd-8a1f-0410-8b47-8ef2f437770f
This commit is contained in:
Bart Van Assche
145
scst/README
145
scst/README
@@ -1352,70 +1352,48 @@ The steps involved in configuring ALUA are:
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As an example, in a H.A. setup with two systems each having one InfiniBand
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HCA controlled by the ib_srpt driver and where each system exports two LUNs
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could be configured as follows:
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the following configuration can be used in scst.conf on both systems:
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own_tgt_id=1
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other_tgt_id=2
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cd /sys/kernel/scst_tgt/device_groups
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echo del dgroup1 >mgmt
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echo del dgroup2 >mgmt
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echo create dgroup1 >mgmt
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echo add disk01 >dgroup1/devices/mgmt
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echo create tgroup1 >dgroup1/target_groups/mgmt
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echo ${own_tgt_id} >dgroup1/target_groups/tgroup1/group_id
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echo add ib_srpt_0 >dgroup1/target_groups/tgroup1/mgmt
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echo ${own_tgt_id} >dgroup1/target_groups/tgroup1/ib_srpt_0/rel_tgt_id
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if [ ${own_tgt_id} = 1 ]; then
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echo 1 >dgroup1/target_groups/tgroup1/preferred
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fi
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echo create tgroup2 >dgroup1/target_groups/mgmt
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echo ${other_tgt_id} >dgroup1/target_groups/tgroup2/group_id
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echo add ib_srpt_0-other >dgroup1/target_groups/tgroup2/mgmt
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echo ${other_tgt_id} >dgroup1/target_groups/tgroup2/ib_srpt_0-other/rel_tgt_id
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if [ ${other_tgt_id} = 1 ]; then
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echo 1 >dgroup1/target_groups/tgroup2/preferred
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fi
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echo create dgroup2 >mgmt
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echo add disk02 >dgroup2/devices/mgmt
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echo create tgroup1 >dgroup2/target_groups/mgmt
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echo ${own_tgt_id} >dgroup2/target_groups/tgroup1/group_id
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echo add ib_srpt_0 >dgroup2/target_groups/tgroup1/mgmt
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echo ${own_tgt_id} >dgroup2/target_groups/tgroup1/ib_srpt_0/rel_tgt_id
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if [ ${own_tgt_id} = 2 ]; then
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echo 1 >dgroup2/target_groups/tgroup1/preferred
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fi
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echo create tgroup2 >dgroup2/target_groups/mgmt
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echo ${other_tgt_id} >dgroup2/target_groups/tgroup2/group_id
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echo add ib_srpt_0-other >dgroup2/target_groups/tgroup2/mgmt
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echo ${other_tgt_id} >dgroup2/target_groups/tgroup2/ib_srpt_0-other/rel_tgt_id
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if [ ${other_tgt_id} = 2 ]; then
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echo 1 >dgroup2/target_groups/tgroup2/preferred
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fi
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DEVICE_GROUP dgroup1 {
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DEVICE disk01
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The second system in the same H.A. setup can be configured with the same
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commands but with the values of ${own_rel_tgt_id} and ${other_rel_tgt_id}
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swapped.
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TARGET_GROUP tgroup1 {
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group_id 256
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preferred 1
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state active
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TARGET fe80:0000:0000:0000:0002:c903:00fa:b7e1 {
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rel_tgt_id 1
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}
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}
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TARGET_GROUP tgroup2 {
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group_id 257
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state standby
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TARGET fe80:0000:0000:0000:0002:c903:00fa:b7f2 {
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rel_tgt_id 2
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}
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}
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}
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The result of the above commands is:
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DEVICE_GROUP dgroup2 {
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DEVICE disk02
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TARGET_GROUP tgroup1 {
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group_id 256
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state standby
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TARGET fe80:0000:0000:0000:0002:c903:00fa:b7e1 {
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rel_tgt_id 1
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}
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}
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TARGET_GROUP tgroup2 {
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group_id 257
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preferred 1
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state active
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TARGET fe80:0000:0000:0000:0002:c903:00fa:b7f2 {
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rel_tgt_id 2
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}
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}
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}
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$ find -type f | grep -v '/mgmt$' | cut -c3- | sort | \
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while read f; do echo $f = $(head -n 1 $f); done
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dgroup1/target_groups/tgroup1/group_id = 1
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dgroup1/target_groups/tgroup1/ib_srpt_0/rel_tgt_id = 1
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dgroup1/target_groups/tgroup1/preferred = 1
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dgroup1/target_groups/tgroup1/state = active
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dgroup1/target_groups/tgroup2/group_id = 2
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dgroup1/target_groups/tgroup2/ib_srpt_0-other/rel_tgt_id = 2
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dgroup1/target_groups/tgroup2/preferred = 0
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dgroup1/target_groups/tgroup2/state = active
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dgroup2/target_groups/tgroup1/group_id = 1
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dgroup2/target_groups/tgroup1/ib_srpt_0/rel_tgt_id = 1
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dgroup2/target_groups/tgroup1/preferred = 1
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dgroup2/target_groups/tgroup1/state = active
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dgroup2/target_groups/tgroup2/group_id = 2
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dgroup2/target_groups/tgroup2/ib_srpt_0-other/rel_tgt_id = 2
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dgroup2/target_groups/tgroup2/preferred = 0
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dgroup2/target_groups/tgroup2/state = active
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Checking the Target Configuration
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.................................
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@@ -1446,7 +1424,7 @@ configured on the target:
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# sg_rtpg /dev/sdb
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Report target port groups:
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target port group id : 0x1 , Pref=1
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target port group id : 0x100 , Pref=1
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target port group asymmetric access state : 0x00
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T_SUP : 0, O_SUP : 0, LBD_SUP : 0, U_SUP : 1, S_SUP : 1, AN_SUP : 1, AO_SUP : 1
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status code : 0x02
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@@ -1454,7 +1432,7 @@ Report target port groups:
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target port count : 01
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Relative target port ids:
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0x01
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target port group id : 0x2 , Pref=0
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target port group id : 0x101 , Pref=0
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target port group asymmetric access state : 0x00
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T_SUP : 0, O_SUP : 0, LBD_SUP : 0, U_SUP : 1, S_SUP : 1, AN_SUP : 1, AO_SUP : 1
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status code : 0x02
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@@ -1463,6 +1441,24 @@ Report target port groups:
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Relative target port ids:
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0x02
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The relative target port ID and the target port group ID for a certain path
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can be queried e.g. as follows:
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# sg_vpd -p di /dev/sdb
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Device Identification VPD page:
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Addressed logical unit:
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designator type: T10 vendor identification, code set: ASCII
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vendor id: SCST_FIO
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vendor specific: 27cddc71-disk01
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designator type: EUI-64 based, code set: Binary
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0x3237636464633731
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Target port:
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designator type: Relative target port, code set: Binary
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Relative target port: 0x1
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designator type: Target port group, code set: Binary
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Target port group: 0x100
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Initiator Support
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.................
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@@ -1472,14 +1468,37 @@ modify at least the following in /etc/multipath.conf to enable implicit ALUA:
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* hardware_handler "1 alua"
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* prio alua
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* path_grouping_policy group_by_prio
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* path_checker tur
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Note: newer versions of multipathd support a parameter called
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"detect_prio". It can be more convenient to enable this parameter instead of
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setting the parameter "prio" to "alua" for only those LUNs that support ALUA.
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# multipath -ll
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23237636464633731 dm-3 SCST_FIO,disk01
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size=1.0G features='3 queue_if_no_path pg_init_retries 50' hwhandler='1 alua' wp=rw
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|-+- policy='service-time 0' prio=1 status=active
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| `- 10:0:0:0 sdd 8:48 active ready running
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`-+- policy='service-time 0' prio=130 status=enabled
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`- 11:0:0:0 sde 8:64 active ready running
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23133326137346538 dm-4 SCST_FIO,disk02
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size=1.0G features='3 queue_if_no_path pg_init_retries 50' hwhandler='1 alua' wp=rw
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|-+- policy='service-time 0' prio=130 status=active
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| `- 10:0:0:2 sdn 8:208 active ready running
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`-+- policy='service-time 0' prio=1 status=enabled
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`- 11:0:0:2 sdp 8:240 active ready running
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The following information can be derived from the above output:
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* That the hardware handler (hw_handler) has been set to "1 alua".
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* That multipathd created two priority groups - one with priority 1 and one
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with priority 130.
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* That the SRP path with SCSI host number 10 will be used for communication
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with LUN "disk01" and that the SRP path with SCSI host number 11 will be used
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for communication with LUN "disk02".
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More information about how to configure the device mapper and the scsi_dh_alua
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driver can be found in the manual of your Linux distribution ("man
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multipath.conf").
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multipath.conf", "man multipath" and "man multipathd").
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Windows initiator systems support ALUA from Windows Server 2008 on. For more
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information about ALUA support in Windows Server, see also:
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