Sun StorageTek Common Array Manager
Software Installation Guide
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Planning Your Storage Configuration
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This chapter introduces you to the Sun
StorageTek Common Array Manager storage components. It contains the
following sections:
For more information
about the concepts introduced in this chapter, see the appropriate
topic in the online help.
Storage Array Configuration Components
The array management software configures
both physical and logical storage components. The components of a
storage array configuration are as follows.
- Initiator - A port on
a Fibre Channel (FC) host bus adapter (HBA) that allows a host to gain
access to the storage array. The initiator has a World Wide Name (WWN)
that is globally unique.
- Host - A data host,
or server with one or more initiators, that stores its data on arrays.
You can define volume-to-logical unit number (LUN) mappings to an
individual host or assign a host to a host group.
- Host group - A
collection of hosts that share access to the same volumes.
- Storage domain -A
logical entity used to partition storage. You need to purchase a
license for the number of domains you need, depending on your array.
- Storage profile - A defined set of characteristics for a storage
pool. You can choose from the set of preconfigured profiles or create a
new one.
- Storage pool - A collection of volumes that
share a profile defining a common configuration.
- Volumes - A division of a storage pool,
consisting of virtual disks, representing the storage space that is
used by the data hosts in the environment.
- Disk - A non-volatile, randomly addressable,
rewriteable data storage device. Physical disks are managed as a pool
of storage space for creating volumes.
- Virtual disks - Also called a redundant
array of independent disks (RAID) set, a collection of locations in the
memory of more than one physical disk. The storage array handles a
virtual disk as if it were an actual disk.
- Tray - An enclosure
that contains a varying number of disks, depending on your array.
In addition to the
basic elements of your storage configuration covered in this guide, you
can add advanced, premium features to your configuration. These
features require the purchase of licenses. The following premium
features are described in the online help and user guide:
- Snapshots
are copies of the data in a volume. They offer a high-availability
alternative to backups because you do not need to take the array
offline to create the snapshot, and you can store the snapshots in less
space than the original data.
- Volume copies are copies of the complete contents of one
data volume that are located on another data volume on the same array.
- Replication sets are
the association between primary and secondary volumes. The secondary
volume contains a complete copy of the data on the primary volume. The
data replication software continuously replicates the data between
volumes in a replication set.
Partitioning Storage Using Storage Domains
Storage domains, also called sets or storage
partitions, enable you to partition storage to allow hosts or host
groups access to specific volumes. Data hosts, such as a data base
server, initiate data to store in volumes through the physical host
ports (or initiators), residing on host HBAs. Volume-to-LUN mapping
enables you to specify the host or host group that can access a
specific volume on your storage array.
Note - Storage domains for LUN-mapping require the
purchase and activation of a license. (Exception - the Sun StorageTek
6130 array includes some free storage domains to start.) The role of
the free default domain is discussed below.
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The is a free default
domain with limited functions noted below. But to map specific
initiators to specific volumes, you need to activate a premium license
for a storage domain. Usually your need for premium licenses will be
determined at the time you order your array.
The Default Domain
A non-premium, default
storage domain exists to include the following:
- All host groups and
hosts that are not explicitly mapped to a volume.
- All volumes that have
a default volume-to-LUN mapping assigned.
- All unmapped,
automatically detected initiators.
Any volumes within the
default storage domain can be accessed by all hosts and host groups
within that storage domain.
Note - If you only use the default domain, you
cannot configure software features such as profiles, pools, initiators,
host groups, LUN-mapping, and virtual disks.
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Premium Storage Domains
Premium storage
domains define a volume-to-logical unit number (LUN) mapping, which
will allow you to specify the host or host group that will have access
to a particular volume in your storage array. The storage domain
designates that only the selected host or host group has access to that
particular volume through the assigned LUN.
When the storage
domain consists of a volume mapped to a host group, it can enable hosts
with different operating systems (heterogeneous hosts), to share access
to a storage volume. A host within a host group can be mapped
separately to a different volume.
A storage domain can
contain up to 256 volumes. A volume can be included in only one storage
domain and each LUN, from 0 to 255, can only be used once per storage
domain.
Note: Not all
operating systems support up to 256 LUN IDs. See the documentation for
your operating system for more information.
FIGURE 4-1 shows how
storage domains can be used to partition storage. It depicts a storage
array configured with three storage domains, Storage Domain 1, Storage
Domain 2, and Storage Domain 3.
The following
figure shows one host group and two hosts belonging to the same storage
domain. A second host group has two hosts, each beloging to a separate
storage domain.
FIGURE
4-1 Storage Array With Three Domains and Four Data
Hosts
Storage Domain 1
consists of two volumes, Marketing and Sales, that are mapped to Host
Group X. Host Group X contains two hosts, Host A and Host B. All
initiators associated with Host A and Host B, within Host Group X, have
access to volume Marketing by way of LUN ID 1 and to volume Sales by
way of LUN ID 2.
Storage Domain 2
consists of one volume, Engineering, that is mapped to Host Group Y.
Host Group Y contains two hosts, Host C and Host D. By virtue of being
associated with any host within Host Group Y, all initiators associated
with Host C and Host D have access to volume Engineering by way of LUN
ID 1.
Storage Domain 3
consists of one volume, Test, that is mapped to Host D. All initiators
associated with Host D have access to volume Test by way of LUN ID 2.
Note that Host D is a member of Host Group Y; however, since volume
Test is mapped directly to Host D and not to Host Group Y, Host D is
the only member of Host Group Y that can access volume Test.
Note - LUN IDs must be unique within a storage
domain.
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For more information
about storage domains and LUN mapping, see the online help.
Best Practices - Storage
Configuration
When configuring a storage array, you need
to determine how to organize and allocate the total storage capacity
into volumes and share those volumes among your data hosts. As you plan
your storage configuration, it is important that you consider the
following requirements for your site:
- Performance
requirements - You can optimize I/O activity by selecting a predefined
storage profile with different characteristics or by creating a custom
profile.
- Access requirements -
You can use storage domains to organize and allocate storage so that
only certain hosts have access to volumes. Volumes in a storage domain
can be accessed only by hosts and host groups that are in the same
storage domain. You can associate a storage domain with individual
hosts or with a host group.
- Combination
of redundancy with performance - To maximize both performance
and redundancy, a combination of RAID levels is necessary. The data
striping provided by RAID 0 is a cost-effective way to create high
levels of performance in a disk array, and having multiple copies of
data through data mirroring provided by RAID 1 is the best way to
create redundancy. By combining RAID 1 with RAID 0, you can take
advantage of both features.
To combine disk
mirroring with disk striping, configure RAID 1 with more than two
drives. The firmware automatically creates a RAID 1+0 virtual disk.
- Storage defaults - The default storage profile, storage pool,
and storage domain are configured as follows:
- The default storage
profile configures associated volumes with a RAID-5 level, default
segment size, enabled read-ahead mode, FC disk type, and a variable
number of drives.
- The default storage
pool uses the default profile (RAID-5) and groups all volumes with the
same storage characteristics, as defined by the storage profile.
- The default domain has no restrictions and allows all
hosts and host groups to share access to the same volumes. If you want
to restrict access to volumes from certain hosts, you should use
storage domains and not the default domain.
- Using profiles and
pools - You must plan your configuration to determine what storage
profile and storage pool to use. For more information, see Planning
Volumes and related topics in the online help.
Sun StorageTek Common Array Manager
Software Installation Guide
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819-7035-12
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Copyright ©
2006, Sun Microsystems, Inc. All Rights Reserved.