As solid-state drive deployment grows, storage administrators will be eager to maximize the use of this expensive, high-performance storage. One way to accomplish this is through automated storage tiering, which moves the data that is used the most often to the fastest available storage.
The concept of storage tiers is relatively simple: pairing different types of data to appropriate types of storage media to reduce costs. For example, mission-critical applications are often stored on high-speed Fibre Channel or SCSI drives, while data used less frequently can go to a second tier of SATA drives. Infrequently used data can be stored offline on tape or removable drives.
EMC has now entered the ring with its Fully Automated Storage Tiering (FAST) software, which continuously monitors actual use of storage and recommends on what tier data should reside. Data can be moved automatically and transparently to the appropriate storage tier, and administrators can schedule moves for a particular time; for instance, data needed to generate month-end reports could be moved to faster storage when reports need to be run, then relegated to slower storage for the rest of the month.
FAST works on EMC Symmetrix V-Max, Clariion CX4 and Celerra NS storage systems, with support for Symmetrix DMX-4 later this year. Here are some recommendations on using it to optimize your EMC storage systems for highest performance at lowest cost.
Storage administrators must decide how many volumes need to be high speed, and whether they all need to be high speed at the same time. FAST currently moves data at the logical unit (LUN) level on Symmetrix and Clariion. The entire LUN, which is typically seen as a volume by the server attached to the storage, is moved together.
While some types of data, such as database indices, may already be in separate LUNs, administrators will want to create separate LUNs for any data that requires high-speed storage. Because SSD storage is relatively small, at 300 gigabytes per drive, it may not be possible to migrate large LUNs to the faster tier, depending on the total SSD storage installed.
However, FAST software for the Celerra platform supports moving data at the file level rather than at the logical unit level, providing greater flexibility. Only those files that are used the most often are moved to faster storage, not the entire volume. This means that considerably less planning is required before using FAST because data doesn’t have to be placed in specific volumes.
This year, FAST for Symmetrix and Clariion will change from moving entire LUNs to moving data at the block level. This level of granularity offers more flexibility, allowing most data to reside on lower-cost SATA storage.
There is virtually no planning required before implementing block-level FAST because it is transparent to the server. Any data in use will be automatically moved to SSD storage.
EMC offers a simple wizard-based installation of FAST. Once the SSDs are installed and the wizard has run, FAST is ready to go. You simply run through the nine steps of the wizard, setting options for how to move data, what tiers to use, the time and days of the week to analyze data movement, the times and days of the week to actually move data, and QoS policy settings.
The FAST Configuration Wizard leads the administrator through nine simple steps to configure the program. In a standard configuration, most admins will just hit ‘next’ at most steps.
The last step is to review the summary of the settings made through the wizard.
Although EMC is a relative latecomer to automated storage tiering with FAST, it offers features that other tiering systems don’t. For example, Quality of Service levels allow administrators to specify not only the storage tier for important data, but how much of the total available bandwidth of the storage area network is allocated to that data, as well as how much available cache is given to particular data.
FAST also offers a set of analysis tools to monitor storage usage and recommend which LUNs would benefit most from being moved to SSD. This application can make recommendations and then carry out any changes that are approved — including both scheduling temporary moves and movement of LUNs on demand.
Creating a time window to move a specific LUN from high-speed to low-cost storage is simple.
The first version of FAST is a good start, but administrators will need to make some fairly extensive changes to optimize it. Block-level FAST won’t require changing LUNs around to move only the needed data, so think about holding off on FAST for Symmetrix and Clariion until this becomes available later this year. However, administrators may still wish to move LUNs to SSD if they are specific to a cyclic application that needs to be fast only once a month.
For storage administrators who want to get the most out of their new SSD drives, FAST is the way to go. Because the FAST system takes advantage of the QoS features recently added to EMC systems, older versions of EMC hardware will not work with FAST.