Data Storage Networks
TCS 822
VIII sem
By
Navin Garg
Intelligent Storage Systems
• As the technology is advancing a new set of
storage solutions , known as Intelligent
Storage Systems have evolved.
• These storage systems have large amount of
memory , multiple Input Output paths & use
advanced algorithms to meet the
requirements of performance sensitive
applications
Intelligent Storage Systems
Components of an Intelligent Storage Systems
Intelligent Storage Systems have following
components
• Front End
• Cache
• Back End
• Physical Disk
Intelligent Storage Systems
Intelligent Storage Systems
• Front End
• The front end provides the interface between
the storage system and the host.
• It consists of two components: front-end ports
and front-end controllers.
• The front-end ports enable hosts to connect
to the intelligent storage system.
• Front End has multiple ports so that large
number of hosts can connect to the System
Intelligent Storage Systems
Front End Controllers
• They are used to route data to cache & from
cache through internal Bus system
Cache
Cache improves Input Output performance of
Intelligent Storage systems
Intelligent Storage Systems
• In cache, CPU stores data Temporarily . It
reduces time required to execute I/O request.
• Cache improves storage system performance
by isolating hosts from the mechanical delays
associated with physical disks.
If Data is found in the Cache it is known as a Hit.
If Data is not found in Cache it is known as a
Miss
Intelligent Storage Systems
Intelligent Storage Systems
Intelligent Storage Systems
• Write Operations with Cache
• Write Back cache
Data is Updated in Cache. Later data from several
writes is committed to the disk. Write response
time is much better.
• Write Through cache
Data updated in cache is immediately written to the
disk. Write response time is longer because of
disk operation.
Intelligent Storage Systems
• Cache Management
Cache is expensive resource. When cache is
filled up some pages have to be freed up to
accommodate new data
Two commonly used algorithms
Least recently used(LRU)
Most recently Used(MRU)
Intelligent Storage Systems
• Cache data protection
Cache is a volatile memory . Hence loss of power
or a cache failure will cause loss of
uncommitted data. This can be dealt in the
following way
Cache Mirroring
Cache Vaulting
Intelligent Storage Systems
• Back End
Back end provides an interface between cache &
Physical disk.
It has two components
Back end ports
Back end Controllers
Intelligent Storage Systems
• Physical Disk
Physical disks provide persistent data storage.
Intelligent storage systems supports variety of
disk drives with different speed & types
Intelligent Storage Systems
• ASSIGNMENT
• Research Cache Coherency mechanism &
explain how they address the environment
with multiple Shared caches.
• Research various cache parameters: cache
page size, cache allocation , cache prefetch
size & write aside size