What is RAID?
RAID stands for Redundant Array of Inexpensive Disks. That means
that RAID is a way of logically putting multiple disks together into a single
array. The idea then is that these disks working together will have the speed
and/or reliability of a more expensive disk. Now, the exact speed and
reliability you'll achieve from RAID depends on the type of RAID you're
using.
Software
vs Hardware?
Software RAID
Software
RAID is an included option in all of Stead fast's dedicated servers. This means
there is NO cost for software RAID 1, and is highly recommended if you’re using
local storage on a system. It is highly recommended that drives in a RAID array
be of the same type and size.
Software-based RAID will leverage some of the system’s computing power to manage the RAID configuration. If you’re looking to maximize performance of a system, such with a RAID 5 or 6 configuration, it’s best to use a hardware-based RAID card when you’re using standard HDDs.
Hardware
RAID
Hardware-based
RAID requires a dedicated controller installed in the server. Steadfast
engineers will be happy to provide you with recommendations regarding which
hardware RAID care is best for you that is based on what RAID configuration you
want to have. A hardware based RAID card does all the management of the RAID array(s),
providing logical disks to the system with no overheard on the part of the
system itself. Additionally, hardware RAID can provide many different types of
RAID configurations simultaneously to the system. This includes providing a
RAID 1 array for the boot and application drive and a RAID-5 array for the
large storage array.
When Should I Use RAID?
- RAID is extremely useful if uptime and availability are important to you or your business. Backups will help insure you from a catastrophic data loss. But, restoring large amounts of data, like when you experience a drive failure, can take many hours to perform. Those backups could be hours or days old, costing you all the data stored or changed since the last backup. RAID allows you to weather the failure of one or more drives without data loss and, in many cases, without any downtime.
- RAID is also useful if you are having disk IO issues, where applications are waiting on the disk to perform tasks. Going with RAID will provide you additional throughput by allowing you to read and write data from multiple drives instead of a single drive. Additionally, if you go with hardware RAID, the hardware RAID card will include additional memory to be used as cache, reducing the strain put on the physical hardware and increase overall performance.
Note:
We generally do not advise using a hardware RAID card for SSD volumes, as the
additional cache isn’t necessary because of the speed of the SSDs themselves.
What Type of RAID Should I Use?
- No RAID - Good if you are able to endure several hours of downtime and/or data loss due while you restore your site from backups.
- RAID 0 - Good if data is unimportant and can be lost, but performance is critical (such as with cache).
- RAID 1 - Good if you are looking to inexpensively gain additional data redundancy and/or read speeds. (This is a good base level for those looking to achieve high uptime and increase the performance of backups.)
- RAID 5/6 - Good if you you have Web servers, high read environments, or extremely large storage arrays as a single object. This will perform worse than RAID 1 on writes. If your environment is write-heavy, or you don't need more space than is allowed on a disk with RAID 1, RAID 1 is likely a more effective option.
- RAID 10 - A good all-around solution that provides additional read and write speed as well as additional redundancy.
What
Does RAID Not Do?
- RAID does not equate to 100% uptime. Nothing can. RAID is another tool on in the toolbox meant to help minimize downtime and availability issues. There is still a risk of a RAID card failure, though that is significantly lower than a mechanical HDD drive failure.
- RAID does not replace backups. Nothing can replace a well planned and frequently tested backup implementation!
- RAID will not protect you against data corruption, human error, or security issues. While it can protect you against a drive failure, there are innumerable reasons for keeping backups. So do not take RAID as a replacement for backups. If you don’t have backups in place, you’re not ready to consider RAID as an option.
- RAID does not necessarily allow you to dynamically increase the size of the array. If you need more disk space, you cannot simply add another drive to the array. You are likely going to have to start from scratch, rebuilding/reformatting the array. Luckily, Steadfast engineers are here to help you architect and execute whatever systems you need to keep your business running.
- RAID isn’t always the best option for virtualization and high-availability failover. In those circumstances, you will want to look at SAN solutions, which Steadfast also provides.
