NAS vs SAN

NAS (Network Attaches Storage)

• Has a network card directly attaches to a switch or router on a network
• It can be accesible from anywhere to use as a shared drive
• Used in homes and small to medium-size businesses
• The main disadvantages of the NAS is SPOF. For ex: if the power supplies fail then it is not accessible. (search: Probably there are ways to run NAS in HA mode, research it)

SAN (Storage Area Network)

• A special, high speed network that stores and provides access to large amounts of data
• Dedicated network consists multiple, disk arrays, switches and servers (`search: what is disk array?à)
• SANs are fault tolerant
• Data is shared among several disk arrays
• When servers access this data as if it was a local hard drive. Because thats how operating system recognize SAN (search: Why is that? )
• Highly scalable
• High speed because devices interconnected using fibre channel. Fibre channel is fiber optics. Speeds between 2Gbit/s - 128 Gbit/s, it is extremely fast
• Some SAN uses iSCSI instead of fibre channel. Because it is cheaper. It is a cheaper alternative to using fibre channel, but not as fast as it.
• SANs are not affected by network traffic, such as bottlenecks in a local area network. This is because SANs arent really a part of local area network, it is partitioned off. It is basically a network all by itself
• SANs are expensive

Things to Search

• iSCSI, NFS etc.

• Disk Array

• HA in NAS

• Files vs block storage access in both of them

• Redundant copy of disk, prevents data loss

• Types of RAIDs are RAID0, RAID1, RAID5, RAID10

RAID

RAID 0 (Striping)

• Not fault tolerant
• Data is sptriped across multiple disks
• Advantage is speed

RAID 1 (Mirroring & Duplexing)

• Is fault tolerant
• Data is copied on more than 1 disk

RAID 5 (Striping with parity)

Probably the most common setups used. Because it is fast and stores large amount of data

• TODO