Flash Drives in DMX

Posted by Diwakar

EMC announce Flash Drive support in CX-4 (A new generation CLARiiON) and DMX-4. EMC started supporting TIER 0 with Flash Drive. Flash drives provide maximum performance for latency sensitive applications. Flash drives, also referred to as solid state drives (SSD), contain no moving parts and appear as standard Fibre Channel drives to existing Symmetrix management tools, allowing administrators to manage tier 0 without special processes or custom tools. Tier 0 Flash storage is ideally suited for applications with high transaction rates and those requiring the fastest possible retrieval and storage of data, such as currency exchange and electronic trading systems, or real time data feed processing.

A Symmetrix DMX-4 with Flash drives can deliver single-millisecond application response times and up to 30 times more IOPS than traditional 15,000 rpm Fibre Channel disk drives. Additionally, because there are no mechanical components, Flash drives require up to 98 percent less energy per IOPS than traditional disk drives. Database acceleration is one example for Flash drive performance impact. Flash drive storage can be used to accelerate online transaction processing (OLTP), accelerating performance with large indices and frequently accessed database tables. Examples of OLTP applications include Oracle and DB2 databases, and SAP R/3. Flash drives can also improve performance in batch processing and shorten batch processing windows.

Flash drive performance will help any application that needs the lowest latency possible. Examples include

· Algorithmic trading

· Currency exchange and arbitrage

· Trade optimization

· Realtime data/feed processing

· Contextual web advertising

· Other realtime transaction systems

· Data modeling

Flash drives are most beneficial with random read misses (RRM). If the RRM percentage is low, Flash drives may show less benefit since writes and sequential reads/writes already leverage Symmetrix cache to achieve the lowest possible response times. The local EMC SPEED Guru can do a performance analysis of the current workload to determine how the customer may benefit from Flash drives. Write response times of long distance SRDF/S replication could be high relative to response times from Flash drives. Flash drives cannot help with reducing response time due to long distance replication. However, read misses still enjoy low response times.

Flash drives can be used as clone source and target volumes. Flash drives can be used as SNAP source volumes. Virtual LUN Migration supports migrating volumes to and from Flash drives. Flash drives can be used with SRDF/s and SRDF/A. Metavolumes can be configured on Flash drives as long as all of the logicals in the metagroup are on Flash drives.

Limitations and Restrictions of Flash drives:

Due to the new nature of the technology, not all Symmetrix functions are currently supported on Flash drives. The following is a list of the current limitations and restrictions of Flash drives.

Delta Set Extension and SNAP pools cannot be configured on Flash drives.
• RAID 1 and RAID 6 protection, as well as unprotected volumes, are currently not supported with Flash drives.
• TimeFinder/Mirror is currently not supported with Flash drives.
• iSeries volumes currently cannot be configured on Flash drives.
• Open Replicator of volumes configured on Flash drives is not currently supported.
• Secure Erase of Flash drives is not currently supported.
• Compatible Flash for z/OS and Compatible Native Flash for z/OS are not currently supported.
• TPF is not currently supported.


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