The disks can be replaced and the parity stripe rebuilt online.
Vendor-Specific RAID
Once we cross over into the world of SAN hardware, there are a number of variations on
the concept of RAID.Most SAN vendors have their own specifications that exceed or
extend the data-protection capabilities of the standard RAID configurations. These nonstandard
configurations usually maximize performance as well, without sacrificing
data-protection capabilities.
Remote Storage
As long as storage is attached directly to a server, even via an external SCSI cabinet or a
portable USB hard drive, there is a certain level of control that a DBA maintains. Once
remote storage is used, control over I/O specifics can become difficult for a DBA. There
are two basic types of remote storage: network-attached storage (NAS) and a storage area
network (SAN).
NAS
The most basic of remote storage, NAS is nothing more than a set of disks with a basic
operating system to make them appear on the network as if they were drives being
shared from a full-blown server. NAS is certainly cost-effective; however, NAS devices are
generally not designed for robust data protection.
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