What is Mirroring? – Storage Basics-7

Mirroring
is the process to provide redundancy. Data will be mirrored from one disk to
another so that it can provide the fault tolerance in case of disk failure:-

There are two types of mirroring as mentioned below:-

1. Instant Copying: – It mirrors the data
locally to the different hard disk in the same enclosure. It can provide
redundancy but to a limited extend as it cannot prevent data lose at the time
of complete enclosure failure.

2. Remote Mirror: – In remote mirroring,
the data will be copied to the hard disk on the different enclosure which may
be located on different data center.

· Synchronous
Remote Mirroring: – In synchronous mirroring, server sent the data to
the disk-1 and then it mirror the data to Disk-2. Disk- will only send the acknowledgement to
server only after complete mirroring of data.

· Asynchronous
Remote Mirroring:- In asynchronous mirroring, Disk-1 will send the
acknowledgement to server once all the data is written on it and simultaneously
it will mirror the data to Disk-2. Disk-1 will not wait for the acknowledgement
from disk-2 and will send the acknowledgement to server.