RAID 0 is used to improve a server’s performance. It’s also known as “disk striping.” With RAID 0, data is written across several disks. This means the work that the computer is doing is handled by multiple disks rather than just one, increasing performance because multiple drives are reading and writing data, improving disk I/O. A minimum of two disks is required. The downside is that there is no fault tolerance. If one disk fails, then that affects the entire array and the chances for data loss or corruption increases.
Yellow = Data
RAID 1 is a fault-tolerance configuration known as “disk mirroring.” With RAID 1, data is copied from one disk to another, creating a mirror of the disk. If one disk crashes, the other can keep working. It’s the simplest way to implement fault tolerance and it’s relatively low cost.
The drawback is that RAID 1 causes a slight drag on performance. A minimum of two disks is required for RAID 1 hardware implementations. With software RAID 1, instead of two physical disks, data can be mirrored between volumes on a single disk. Also, RAID 1 cuts total disk capacity in half: If a server with two 1TB drives is configured with RAID 1, then total storage capacity will be 1TB not 2TB.
Yellow = Data
Blue = Fault tolerant information.
RAID 5 is by far the most common RAID configuration for business servers and enterprise NAS devices. This RAID level provides better performance than mirroring as well as fault tolerance. With RAID 5, data and parity (which is additional data used for recovery) are striped across three or more disks. If a disk gets an error or starts to fail, data is recreated from this distributed data and parity block— seamlessly and automatically. Essentially, the system is still operational even when one disk crashes and until you can replace the failed drive. Another benefit of RAID 5 is that it allows many NAS and server drives to be “hot-swappable” meaning in case a drive in the array fails, that drive can be swapped with a new drive without shutting down the server or NAS and without having to interrupt users who may be accessing the server or NAS. It’s a great solution for fault tolerance because as drives fail (and they eventually will), the data can be rebuilt to new disks as failing disks are replaced. The downside to RAID 5 is the performance hit to servers that perform a lot of write operations. For example, with RAID 5 on a server that has a database that many employees access in a workday, there could be noticeable lag.
Yellow = Data
Blue = Fault tolerant information.
RAID 10 is a combination of RAID 1 and 0 and is often denoted as RAID 1+0 or RAID 0+1. It combines the mirroring of RAID 1 with the striping of RAID 0. It’s the RAID level that gives the best performance, but it is also costly, requiring twice as many disks as other RAID levels, for a minimum of four. This is the RAID level ideal for highly utilized database servers or any server that’s performing many write operations. RAID 10 can be implemented as hardware or software, but the general consensus is that many of the performance advantages are lost when you use software RAID 10.
Yellow = data
Blue = Fault tolerant information
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