Worried about the days long rebuild times of 6, 8, or even 10TB drives? Don't be. Object storage is getting rid of that relic of the 25-year-old RAID architecture. Here's how it works.

What?

RAID arrays are designed to allow one or two individual drives to fail without losing access to the data. Parity data is added to your data to enable data access even after drive failure(s).

The parity+data bits are spread across the drives. The smallest RAID arrays are 4 drives, but 6-8 drives in a RAID stripe is most common. With RAID 5, one drive's worth of capacity is dedicated to parity, while in RAID 6 two drive's worth are.

RAID 5 can handle one drive failure. RAID 6 can handle two failures, or, more likely, one drive failure and one Unrecoverable Read Error (URE)...


...Fortunately for drive vendors, a newer architecture has replaced RAID for large scale systems: object storage. An object is a file plus metadata that normally is stored in a file system. Objects are accessed directly by their ID number, not through a file system.

Losing the file system has many benefits, such as allowing multiple servers to access the same data pool. But compared to RAID, the big advantage is that the data layout is not confined to RAID stripes.

Instead, object storage typically breaks a larger file into several chunks or shards containing data plus parity. The parity can be adjusted so that, for instance, the system can sustain multiple - 4 or 5 commonly - drive failures without data loss or a performance penalty...

Read more: Why do we still rebuild RAID drives? | ZDNet

Posted By: Brink
28 Nov 2016