SAN Latest Interview FAQs - TOP SAN Interview Questions and Answers
> How is fiber channel different from ISCSI?
Fibre Channel and iSCSI each have a distinct place in the IT infrastructure as SAN alternatives to DAS. Fibre Channel generally provides high performance and high availability for business-critical applications, usually in the corporate data center. In contrast, iSCSI is generally used to provide SANs for business applications in smaller regional or departmental data centers.
>What is RAID?
Technology that groups several physical drives in a computer into an array that you can define as one or more logical drive. Each logical drive appears to the operating system as single drive. This grouping enhances the performance of the logical drive beyond the physical capability of the drives.
> Explain different types of RAID? RAID 0: data striping blocks are written sequentially, no redundancy, high performance than single disk access.
RAID 1: Mirroring, data blocks written to both disk at once, 100% redundancy, 100% additional capacity required. Read can be distributed across both the disks to increase performance.
RAID 3: Striping with byte parity, adds parity information to rebuild data in the event of disk failure, high transfer rate and availability with lower capacity required than RAID 1. Transactions performance low because all disks operate in lock step.
RAID 4: striping with block parity, independently accessible disks, data blocks written sequentially to each disk failure. Dedicated parity disk is write bottleneck and leads to poor performance.
RAID 5: Striping with rotational parity, parity blocks written per row and distributed across all disks, parity distribution eliminates single write bottleneck overhead for parity calculation on write supplemented with parallel microprocessors or caching.
> What is storage virtualization?
Storage virtualization is amalgamation of multiple n/w storage devices into single storage unit.
> What is LUN Masking?
A method used to create an exclusive storage area and access control. And this can be achieved by storage device control program.
> What is snapshot?
A snapshot of data object contains an image of data at a particular point of time.
> What is a Point-to-Point Topology?
Point-to point topology provides a simple, direct connection between just two nodes. This topology is the closest approximation to the traditional SCSI topology and provides a direct connection between two nodes, such as between a file server and a disk subsystem. With this topology, the transmitter port on one node os connected directly to the receiver port on the other node.