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Data storage solutions are required to store the data electronically and making it machine readable. Storage is a process through which digital data is saved within a data storage device my means of computing technology. Storage is a mechanism that enables a computer to retain data, either temporarily or permanently.
The most widespread standard for configuring multiple hard disks drives is RAID (Redundant Array of Inexpensive Disks), which comes in a number of standard configurations and non-standard (nested or hybrid) configurations. There is several different way to organize hard drive arrays:
Standard RAID levels
The standard RAID levels comprise a basic set of RAID configurations that employ the techniques of striping, mirroring, or parity to create large reliable data stores from multiple general-purpose computer hard disk drives.
- RAID 0 (stripe set without parity, redundancy of fault tolerance)
- RAID 1 (mirroring)
- RAID 2 (rarely used, stripes data at the bit, rather than block, level)
- RAID 3 (rarely used, byte-level striping with dedicated parity disk)
- RAID 4 (block level striping with a dedicated parity disk)
- RAID 5 (distributed parity)
- RAID 6 (dual parity)
Nested RAID levels
Nested RAID levels are usually numbered using a series of numbers, where the most commonly used levels use two numbers. The first number in the numeric designation denotes the lowest RAID level in the "stack", while the rightmost one denotes the highest layered RAID level.
- RAID 01 (RAID 0+1) (a mirror of stripes)
- RAID 03 (RAID 0+3) (byte-level striping with dedicated parity)
- RAID 10 (RAID 1+0) (a stripe of mirrors)
- RAID 50 (RAID 5+0) (block level striping of RAID0 with the distributed parity of RAID5)
- RAID 60 (RAID 6+0) (block level striping of RAID0 with the distributed double parity of RAID6)
- RAID 100 (RAID 10+0) (a stripe of RAID 10s)
Enterprise redundant RAID configuration will often allow to hot swap drives. Hot swappable drives enable IT engineers to remove a failed drive and replace it with a spare using specialized drive enclosures without having to shut down the system. This is useful in environments where the drive array serves a mission-critical purpose and downtime is not an options.
Various RAID configurations are used in Direct Attached storages (DAS), Network Attached Storage (NAS) and Storage Area Networks (SAN) architectures.
Direct-attached storage (DAS)
Direct-attached storage (DAS) is digital storage directly attached to the computer\server accessing it, as opposed to storage accessed over a computer network (i.e. network-attached storage). DAS was the precursor to NAS. DAS performs better for software programs that require more computing. However, being directly attached, it does not lend itself well to sharing and is complex to manage.
Network-attached storage (NAS)
Network-attached storage (NAS) is a file-level (as opposed to block-level storage) computer data storage server connected to a computer network providing data access to a heterogeneous group of clients. NAS are accessible over a network using an Ethernet connection and file protocols like SMB/CIFS (Server Message Block/Common Internet File System) or NFS (Network File System).
NAS is popular way of creating network file shares within an organization, where authorized personnel often collaborate on the same files or other forms of business information. It can also be used to keep a backup of files in case a local drive gives out and consolidate multimedia libraries, among other use cases where storing and trading files over a local network comes in handy.
Typically, the more high-end the NAS system, the more RAID configuration options are available. High end systems for larger organizations from the likes of Dell EMC, HPE, and NetApp offer a plethora of RAID options that storage administrators can use to meet their file storage capacity, performance and data protection requirements. NAS appliances can utilize RAID technologies, they work well together or completely apart in many cases. Home and enterprise users can create a RAID configurations unless they choose a JBOD (just a bunch of disks) mode.
Performance wise, components that was used to build NAS will define overall performance:
- CPU: budget NAS devices will have low-end processors while enterprise NAS systems are often powered by server grade processors like Intel's line of Xeon CPUs
- RAM: low-end NAS devices can get by with meager amounts of RAM, while high-end systems can offer gigabytes worth of memory to cache up file operations.
- Drives: opting for enterprise NAS grade derives will ensure they deliver reliably fast performance with better read/write speeds and better throughput rates. For the ultimate in performance, some vendors like Dell EMC or Synology offer all-flash NAS arrays outfitted with fast SSDs (solid-state drives).
In a RAID configuration, performance characteristics are governed by the quality and type of hard drives used, type of RAID controller and the RAID level selected. A RAID6 implementation will deliver good read speed while write speeds suffer somewhat because the RAID array needs to store and manage parity information to provide fault tolerance, for example.
What is NAS storage used for?
- File storage and sharing. This is NAS major use case in mid-sized, SMB, and enterprise remote offices. A single NAS device allows IT to consolidate multiple file servers for simplicity, ease of management, and space and energy savings.
- Active archives. Long-term archives are best stored on less expensive storage like tape or cloud-based cold storage. NAS is a good choice for searchable and accessible active archives, and high capacity NAS can replace large tape libraries for archives.
- Big data. Businesses have several choices for big data: scale-out NAS, distributed JBOD nodes, all-flash arrays, and object-based storage. Scale-out NAS is good for processing large files, ETL (extract, transform, load), intelligent data services like automated tiering, and analytics. NAS is also a good choice for large unstructured data such as video surveillance and streaming, and post-production storage.
- Virtualization. Not everyone is sold on using NAS for virtualization networks, but the usage case is growing and VMware and Hyper-V both support their datastores on NAS. This is a popular choice for new or small virtualization environments when the business does not already own a SAN.
- Virtual desktop interface (VDI). Mid-range and high-end NAS systems offer native data management features that support VDI such as fast desktop cloning and data deduplication.