Don’t know your SAN from your NAS? This quick guide will run you through the ten most common types of storage, from internal and external hard drives, to storage area network and network-attached storage, by way of solid state drives (SSDs), magnetic tape storage and RAID…
Internal hard drives
Certainly the most common form of data storage is an internal hard drive – if you’re purchasing a ready-made notebook or workstation, it’ll generally already come included. They allow you to store files in a single computer, and come in the form of a traditional spinning disk hard drive, or more efficient solid state drive (SSD).
Pros: The convenience of internal hard drives is a major plus point, as they usually come bundled in with your new computer. They’re great for use with a single computer, but given proper support, can also be shared among multiple machines.
Cons: Limited capacity is a drawback, as is the fact that without special support, you’re confined to a single computer or server.
External hard drives
As well as internal hard drives, if you’re saving large files, you’re probably familiar with external hard drives. These are used throughout creative and business environments for local backup and archiving of data, and are usually small enough to sit happily on your desk.
Pros: The main upside of external hard drives is that they can be moved around multiple computers and users in your studio or office.
Cons: Just as with internal hard drives, external hard drives can be hamstrung by limited capacity. It can also be incredibly awkward to physically transfer data among multiple computers using external hard drives.
Solid state drives (SSDs)
As mentioned above, solid state storage can come in the form of an internal hard drive that ships with your Mac or other workstation, or as external hard drives. The external, portable variety are used for everyday simple file swapping and local data transfer, and larger capacity drives are often used for more heavy duty work like video processing, relational databases and high-speed data acquisition, either as an internal or external drive.
Pros: The main advantage of solid state storage is that, unlike your traditional spinning disk hard drive, they have no moving parts, which generally means there are fewer components which could potentially fail. They also have high read/write speeds, and the portable, external variety have a small form factor which makes them incredibly portable or chuck-in-your-laptop-bag-able.
Cons: On the downside, solid state storage has limited storage capacity, with many mobile drives topping out at around 1 or 2TB, and cost more than hard drives.
Storage area network (SAN)
If you’re working with large databases, bandwidth-hungry and mission-critical applications, the above options are not the drives you are looking for. Storage area network (SAN) is a cover-all term for a network that gives multiple users block level access (as opposed to file level) to multiple storage devices and arrays, accessible to servers so that the devices appear to the operating system as locally attached devices. SANs are widely used by enterprises working with large amounts of data and apps.
Pros: The main reason you’d want to go for SAN is for consolidated block storage. SAN is also exceptionally reliable, widely available, very tolerant of faults, and super scalable, so you can expand on your SAN as your business grows.
Cons: One minus point with SAN is its high cost, which can be prohibitive to smaller businesses. Traditionally you’d also require a dedicated network, separate from the network supporting desktops. Managing SAN can be quite complex too, which could cause a few headaches.
Fibre Channel is a type of SAN used to connect shared storage to servers. Its high speed means it can often be found in datacentres and offsite storage dealing with large databases, bandwidth-intensive and mission-critical applications.
Pros: Fibre Channel lets you transmit data between devices at super-fast gigabit speeds (often at 1, 2, 4, 8 and 16 gigabit per second rates).
Cons: As it is a SAN though, it can be prohibitively expensive, and complex to manage.
Another type of SAN, iSCSI (or Internet Small Computer Systems Interface, if you’re not in a hurry), is a standard that provides block-level access to storage devices over an Ethernet network. As with Fibre Channel, it’s used for linking data storage facilities, SANs, for offsite storage and mission-critical applications.
Pros: iSCSI lets you transmit data between devices using existing network infrastructure, rather than dedicated cabling, so you can run it over long distances.
Cons: Although, it doesn’t compare as favourably with Fibre Channel when it comes to large database transfers, and is also equally complex to manage.
Network-attached storage (NAS)
Used for data storage and file stores, a NAS is effectively a file server often built as a computer appliance (a purpose-built specialised computer), and tends to be managed remotely, usually by a web-based GUI. The device provides access to storage at file level, rather than at a block level like SAN, using a variety of protocols, such as NFS, SMB/CIFS, and AFP. It provides local area network (LAN) nodes with file-based shared storage through your standard Ethernet connection, giving multiple clients on the network access to the same files.
Pros: NAS is great as it gives fast file access it multiple clients, it’s easy to share data, has high storage capacity, is easy to mirror drives, and lets you consolidate all your resources in one place. Redundancy, backing up copies of files, also means you’re protected against data loss in the event of a disk failure.
Cons: It is, however, less convenient than a storage area network (SAN) for moving large blocks of data.
Disk-to-disk-to-tape (D2D2T) is a backup and archiving system in which, as you may have guessed, data is first copied to backup storage on a disk storage system, then periodically copied again to a tape storage system. It’s often used for incremental backups of data, storage virtualisation, offsite storage and data archiving.
Pros: Upsides are redundancy (which safeguards against data loss), a high read/write speed for quick data transfer, and high capacity (use multiple tapes to your heart’s content).
Cons: The only problem with D2D2T storage is that it’s complex to manage.
A tape drive is a data storage device that reads and writes data on a magnetic tape. You’ll generally find these used for data archiving and offline storage, and are much favoured by the budget-conscious business.
Pros: The main thing tape storage has going for it is its low cost per megabyte. They’re also a fairly portable form of data storage, plus you get unlimited capacity, as you can always add more tapes.
Cons: However, tapes make it inconvenient to quickly recover individual files or groups of files, and you may have to buy quite expensive housing if you have lots of tape.
A redundant array of independent disks (thankfully known more widely by the acronym RAID) is simply a method of combining multiple physical disks into a single unit for performance and/or reliability, and is used in pretty much every SAN, NAS and DAS array. RAID lets you easily swap files, and gives ‘data redundancy’, which essentially means you don’t lose data if a single disk fails, and lets you correct errors to protect against data loss.
Pros: RAID is high speed, high capacity, high data availability storage that’s reliable, secure and gives you fault tolerance in the face of disk failure (ie peace of mind).
Cons: RAID users may unfortunately develop a false sense of security though, with recovery from failure difficult in some systems. And if you’re looking at a high-end optimum system, be prepared for a high price tag.
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