RAID Storage Calculator: How Much Usable Space Do I Get?

Separate sets of independent recordings, or raid, help to combine several cheap disks or solid state drives so that they act as one unit. Rather than save all data on one recording, this system spreads the information through two or more disks forming something called a disk set. Depending on the setup, the arrangement can speed up the pace, increase the reliability or both.

Various levels of raid exist, and each of them implies trade-offs between speed, security and the amount of storage space that is used. For instance, raid 0 splits the incoming data in blocks and spreads them over all the disks. This well boosts the pace of data removal, but indeed it makes the whole system more sensitive to loss of information.

How RAID Makes Disks Faster and Safer

When one recording flops in raid 0, then evrything is lost.

raid 1 works entirely otherwise. It produces a double copy of every block of data on another recording, almost like a mirror. The downside is that the usable capacity matches only the half of the total disk space, because everything is written doubly.

The remaining available space matches the size of the smallest recording from the set.

raid 5 uses several disks, with part of each booked for error correction. If one recording fully flops, the system however can still work. One then can pull the failing recording and replace it.

Some setups even back warm change, so that the system does not need to be turned off for power. Raid 6 is like this, but it can handle more failures. A setup of raid 10 with four disks can provide increased paces for reading and writing and survive even too disk failures.

raid can be set up by means of hardware or software. A hardware controller for raid is a special part, sometimes built into the main board or added as a separate card. It has its own chip for handling the calculations of raid.

Some such hardware controllers own a cache backed by battery, so that data can be written to recording even after a power failure. Software raid rather happens at the level of the operating system.

An important thing to know is that raid does not match a backup. It offers extra safety in real time, so that the data is always mirrored or protected right away. On the other hand, a backup is a copy from a certain time, that can be already several hours old.

Truly, raid is meant for short term safety and to prevent failures, when a recording dies.

Bigger disks allow more storage in the same physical space, but that does not make sets useless. They simply give even bigger capacity in a set of the same size. For folks that save important data like photos or files of clients, combining raid with regular backups is a wise step.

Different levels of raid imply different costs for the used space, so the right choice depends on the needs of theproject, the physical storage setup and the budget.