Setup & User Guide
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DOC-246-GDE-Pivot3 Acuity 2.3 Setup & User Guide-v1.0.docx
Section 10 Host Access Groups
Host Access Group Basics
For application servers to access volumes, the volumes must be assigned to a host access group that the servers are also
associated with. Host access groups are logical representations of the servers that have iSCSI initiators that will connect to
the volumes in the group. By controlling the connection of server to volume, host access groups promote data integrity
and security.
Default Host Access Groups
There are three default host access groups to which servers and volumes may be assigned:
Default Groups Purpose
Chap Only Access Group for aggregating hosts that use CHAP.
Allow Access Group that allows all hosts to write to any associated volume.
Deny Access
Group that prevents write access to associated volumes. New volumes are
placed in this group by default.
Acuity volumes must be assigned a Host Access Group upon creation. When vSTAC volumes are created, they are put into
the Deny Access group by default. This prevents any unintended I/O from getting to the volume until a valid access group
is set up.
BEST PRACTICE:
Set up and use a custom Host Access Group instead of using any of the default groups.
Servers
A host access group can represent a single iSCSI initiator or multiple iSCSI initiators. Host access groups act as a filter to
restrict access to a volume to a given set of servers.
CRITICAL:
When assigning multiple application servers for read/write access to the same volumes, the servers must be aware
via application/hypervisor clustering and/or a clustered file system that they are concurrently accessing the same
volumes. Assigning the same volumes for concurrent read/write access to multiple application servers that are not
cluster-aware will result in data inconsistencies or data-integrity issues on the volume.
IQNs are used to attach iSCSI initiators to the node. Host access groups limit access to volumes to the iSCSI initiators that
are specifically included in a group. Each iSCSI initiator should have a unique IQN on the IP SAN network.
NOTE: A storage volume cannot be deleted until its associated Host Access Group is changed to Deny Access
.
The most common use cases for host access groups are as follows:
Host Access Group Use Case Description
Single application server host
access group
One or more iSCSI initiators in a single application server are
assigned to the host access group.
Each iSCSI initiator is identified by an IQN (iSCSI qualified name)
that is unique within the IP SAN.
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