Storage Area Networks For Dummies®

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Par t II: Designing and Building a SAN
The disadvantages of a host-based solution follow:
✓ Depending on the solution, you may need duplicate servers always
running and sucking up power at the DR site.
✓ Multiple points of management.
✓ Takes up CPU cycles on the host. This is especially true for host-based
solutions which also use the CPU in the host to de-duplicate the data
prior to replication.
✓ Can be complex when you have many servers to protect.
✓ Cannot create consistency groups across servers for data dependencies.
✓ If network quality of service or network throttling is not included with
the solution, host-based replication can suck up all the IP bandwidth
between sites, leaving no network resources available for production or
client access.
✓ Most solutions do not provide a mechanism to encrypt data in flight to
reduce security risks.
Choose a host-based solution when . . .
✓ You have just a few servers, a limited budget, and a server that can be
up all the time at the DR site.
✓ You have many small remote offices, you need to consolidate data protection
at the DR site but have no IT staff at the remote sites, and you
don’t want to use and ship tapes.
✓ The solution provides client-side (host-based) data versioning or data
de-duplication to reduce WAN bandwidth.
✓ The solution can replicate many-to-one to a NAS share or appliance at
the DR site to minimize server requirements at the DR site.
✓ The solution integrates with virtual servers to reduce infrastructure
costs for DR (virtual server-to-virtual server replication).
✓ When the proposed solution is more cost-effective than array-based or
appliance-based solutions and still solves the problem at hand.
Appliance-based data replication solutions
Special-purpose appliances are used with an application-based solution.
Data replication appliances are fairly new in the storage industry and have
become a thorn in the side of many traditional storage vendors who ship
storage array-based solutions. Many companies adopt special-purpose