Volume Configuration; Monitoring An Existing San - Dell EqualLogic FS7500 Technical Manual

workload, then the performance of existing block workloads may be affected as the storage system is
forced to share resources between them.

6.4 Volume configuration

The FS7500 is able to use the entire capacity of a pool and can support files up to 4TB in size. During
configuration of the FS7500, the administrator is allowed to choose the pool that the NAS reserve will
be created in. All FS7500 pairs must use the same pool, and if the pool contains existing volumes,
there must be adequate free space available to create the NAS reserve.
The FS7500 requires a minimum of 250GB of free disk space (NAS reserve) for each controller pair. A
portion of the NAS reserve is reserved space for the system so there must also be sufficient free space
to create a NAS file system to hold user data. Best practices also dictate that a minimum of 5% of total
pool space be kept free to allow normal volume load balancing and distribution to occur automatically.
The amount of NAS reserve can be increased at any time provided there is free pool space.
If the minimum required free disk space is not available, then additional arrays must be added to the
group prior to configuring the FS7500. If additional arrays are added to an existing pool which will be
shared by block and file I/O volumes, then it is recommended that the group be allowed time to
balance existing block volumes across the newly added array(s) before configuring the FS7500.
Depending on the number of existing arrays and volumes, this operation could take several hours (or
longer based on the SAN workload).
The space that is allocated to the FS7500 will determine the number of volumes that are created for
each FS7500 pair. A minimum of two volumes will be created for each controller pair. The maximum
volume size supported by the EqualLogic arrays is 15TB, therefore if the space allocated to the FS7500
is greater than 30TB (i.e., two 15TB volumes), an additional pair of volumes will be created for each
FS7500 controller pair. This process continues until the capacity requirement is satisfied.
Because the volumes that are allocated to the NAS storage pool are also controlled by the FS7500,
many operations that are available for standard block volumes are disabled in Group Manager and CLI
access. This includes options such as replication, snapshots, and the ability to online or offline a
volume.

6.5 Monitoring an existing SAN

SAN HQ is included with every EqualLogic storage system and is ideal for monitoring EqualLogic SANs
over a longer period of time. Administrators can collect data from the SAN and review it to ensure that
there is sufficient storage and I/O capacity for current needs as well as future growth. Figure 6 shows
an example of the SAN HQ user interface and some of the many statistics that it can provide.
Prior to adding a FS7500 to an existing SAN, Dell recommends using SAN HQ to collect statistics about
the existing SAN. Administrators should carefully monitor historical disk capacity usage and trends to
ensure that there will be sufficient free pool space to integrate the FS7500. Administrators should
examine average IOPS over longer periods of time as well as peak IOPS required during short bursts of
high activity. Understanding the sources (i.e. from which hosts) of each type of activity will help the
administrator determine optimal configuration for pools and number of arrays needed.
Administrators should also look at statistics such as Queue Depth by disk and volume to understand
the average number of outstanding I/Os that are waiting for service. Higher numbers indicate higher
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Integrating the Dell EqualLogic FS7500 into an Existing SAN