What kind of storage does the server use?
Depending on your server, the storage can vary but we'll describe the basic storage concepts used.
All servers use some form of RAID for the operating system and storage. The storage sometimes are partitioned from larger raid arrays or have their own raid arrays. Most of the raid configurations support write caching which improves write performance by caching the write data in memory and then copying the data to raid array(s). The three RAID variants used on the servers are RAID 1, 5 and 6. Hard drives in these arrays vary from solid disk drives (SSD) to enterprise class SATA drives.
On the server you usually will only see a "OS drive/C drive". The other array(s) that contains your database and/or video storage are mounted to the C drive as a folder. Typically they are called video or database.
- RAID 1, or disk mirroring, is the process of replicating the data to more than one disk. Both the disks are operational at the same time, so the system can read data from both simultaneously. This enhances the speed of read operations. However, the write operations are slower, as the system executes each write operation twice once on each disk. A minimum of two disks are required for a RAID 1 array. RAID 1 is used to increase reliability of O/S software and sometimes used for a separate array for the database.
- RAID 5 is block-level striping with distributed parity. RAID 5 can tolerate failure of any drive in the array without losing a single byte of stored data. Striping and data are distributed by independent read and write operations. In a "write" operation, data to be recorded is striped across all array members interspersed with a parity block and distributed so as to place one segment containing the parity checksum on a different drive within each striping cycle. Sometimes defined as rotating parity, this scheme is the reason why it doesn't matter which
drive in the array fails. A minimum of three disks are required for a RAID 5 array.
- RAID 6 extends RAID 5 by adding another parity block; thus, it uses block-level striping with two parity blocks distributed across all member disks. RAID 6 can tolerate the concurrent failure of two hard drives while precluding data loss and system downtime. Thus, another moniker for RAID 6 is "double-parity RAID". RAID 6 requires a minimum of four drives, but will typically have a significantly larger number of array members since performance, fault tolerance and cost efficiency are improved with a larger population.
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