The Difference Between RAID 1 and RAID 0 Arrays

Home computer users may be interested in setting up two hard drives in a RAID array in order to store large amounts of data or to provide a relatively fail-proof backup system.

If you’re trying to decide between setting up RAID 1 or a RAID 0 array, here are some notes on the key differences in the technologies.

How Data Is Stored

RAID 1 and RAID 0 arrays store information in completely different ways; RAID 1 arrays mirror data, while RAID 0 arrays stripe data.

Striped Data

Striping data writes sectors across two separate hard drives; if you had two bits of data, it’s helpful to think that one would be written to the first disk and the second bit to the second disk (though this isn’t necessarily true; it does, however, explain the concept quite nicely). There’s no cut in speed when compared to a standard drive (unless a RAID 0 is set up with more than 3 drives, as this is inefficient), but if one of the drives in the array fails, there’s no backup and a user must either pursue data recovery or replace the failed drive in the array and format the remaining drive to get the array set up again.

Mirrored Data

Mirrored hard drives write identical information simultaneously, essentially providing the user with a perfect backup. Again, there’s no cut in speed. Mirrored drives are unlikely to fail at the same time unless they’re being kept in a poor location (and subject to extreme heat) or otherwise mistreated. As long as a user is careful to keep mirrored drives on a protected power supply and safe from physical and heat-related damage, they’re one of the best backup systems that exist.

What This Means For Price

RAID 1 and RAID 0 arrays with two drives cost the same, because the RAID is usually controlled with simple hardware or software. Since you’re buying two drives to hold the same data, one could make the case that a RAID 1 is a worse value than a RAID 0, but the added value of having your data constantly backed up to an identical drive is a huge plus. Factor in that data recovery can cost upwards of $2000, and possibly more on a RAID 0, and the RAID 1 is more valuable for users that intend to use the devices for backup rather than just storage.

There are also RAID 1+0 arrays, which is a RAID 0 set up with an additional two mirroring drives, essentially running to RAID 0s at once. This can be a great choice for computer users who want a great backup system that can still hold a lot of data. When particularly massive amounts of data are being stored, however, a RAID 5 is recommended. RAID 5 arrays are striped data sets, usually with more than 2 hard drives, and a parity drive which enables any failed drive to be switched out without data being lost.

Some commercial RAID 1 and 0 devices include the larger models of Western Digital’s MyBook series.

You can read information on RAID data recovery here.