Using SSDs to Boost Legacy
RAID and Database Performance
Database applications are at
the core of almost every major business today. The unparalleled growth of large
database applications however, has created severe performance issues for end
users. Too many users, too many transactions, and too many queries are slowing
down systems, costing additional business for many and grinding business to a
halt for some.
Often, additional processing power alone will do little or nothing to
improve database performance. This is because the processor, no matter how fast,
finds itself constantly waiting on mechanical storage devices for its data.
While every other component in the "data chain" moves in terms of
computation times and the raw speed of electricity through a circuit, hard
drives move mechanically, relying on physical movement around a magnetic platter
to access information.
When servers wait on storage, users wait
on servers. This is I/O wait time. RAM-based cache is the most common remedy
for I/O wait time on database applications, but comes with its own set of
challenges. Large monolithic RAID systems that incorporate high capacity caches
are prohibitively expensive and cannot be upgraded in a modular fashion.
To
solve this problem, more RAID
manufacturers are partnering with solid state disk companies such as Texas
Memory Systems to deliver a fast external cache system alongside high-capacity
RAID. The RamSan-330 cache system, when installed alongside a RAID device,
provides the fastest access to data for applications and users.
The
combination of RAID and fast RamSan cache accelerates data access by providing a
high-speed data pipeline. By temporarily writing data to fast DDRRAM instead of
conventional rotating disks, the solution drastically increase burst bandwidth
and I/O rates, ensuring that existing storage systems will survive under
immediate pressure. Smart caching algorithms "pre-fetch" data that
users are likely to access, which increases overall performance by enabling
applications to read popular data directly from cache.
Additionally,
the system accelerates the transfer rate of the RAID itself through a process
called "data smoothing." Random data access behaviour is extremely
detrimental to conventional hard disk performance because rotating drives are
optimised for sequential data reads and writes. In tests, while data was reading
and writing to cache at the speed of RAM, the RAID itself was writing data at
The reason is that the external storage cache is smoothing the data by
converting random data patterns to nearly sequential data patterns. Because the
RAID is responding faster, the external cache is more effective, and as a result
the application is responding faster to the user.
This overall
improvement in storage performance will eliminate storage performance
bottlenecks for database applications, accelerating user concurrency, query
times, and transaction rates. As applications and data volumes continue to
expand storage environments, most organisations face tough choices: data
migration challenges, matching capacity and performance requirements, and the
prospect of massive hardware upgrades. Independently scaling storage performance
by adding external cache devices to the storage network alleviates these pains.
Cache systems already have a permanent place in modern IT
environments. As business applications become more demanding, these external
storage cache systems will become more necessary. Monolithic RAID configurations
are not scalable to meet enterprise application needs and are too expensive for
the datacentre looking for performance. Combining the world's fastest RAID
controllers with the world's fastest external storage cache offer high capacity
and high performance while limiting overall cost. ...Texas Memory Systems
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