Friday, January 25, 2008

RAID 5 or 1+ 0 Continued

After reading this article: Smart SOHOs Don't Do RAID I am starting to second guess myself if a RAID is really needed after all.

Sumarrizing from the BytePile Website :

RAID 5 - Most versatile RAID level
RAID Level 5 requires a minimum of 3 drives to implement

Advantages: Highest Read data transaction rate. Medium Write data transaction rate. Low ratio of ECC (Parity) disks to data disks means high efficiency. Good aggregate transfer rate.

Disadvantages: Disk failure has a medium impact on throughput. Most complex controller design. Difficult to rebuild in the event of a disk failure (as compared to RAID level 1). Individual block data transfer rate same as single disk.

Recommended Applications: File and Application servers ? Database servers ? WWW, E-mail, and News servers ? Intranet servers ?

RAID 10 - Very High Reliability combined with High Performance
RAID 10 requires a minimum of 4 drives to implement.

Advantages: RAID 10 is implemented as a striped array whose segments are RAID 1 arrays. RAID 10 has the same fault tolerance as RAID level 1. RAID 10 has the same overhead for fault-tolerance as mirroring alone. High I/O rates are achieved by striping RAID 1 segments. Under certain circumstances, RAID 10 array can sustain multiple simultaneous drive failures. Excellent solution for sites that would have otherwise gone with RAID 1 but need some additional performance boost.

Disadvantages: Very expensive / High overhead. All drives must move in parallel to proper track lowering sustained performance. Very limited scalability at a very high inherent cost.

Recommended Applications: Database server requiring high performance and fault tolerance?

This all sounds good but would I better be served (no pun intented) by a second file server or NAS? This could potential address the need for off site backups while eliminating the need for a RAID. Will or can i take advantages of the performace increases associated with a RAID?

Storage is cheap so a belt and suspenders solution may be a viable way to take care of all my data needs while capitolizing on any performace gains.

Before I started posing this blog I was eyeing the very hackable Buffalo 500GB LinkStation Live that runs Linux. It has been heavily discounted as of late and can be purchased for around $200 USD.

I would have to verify the following:

"In order to make this approach work, one of the two NASes must support scheduled backup to or from a networked drive. Most all NASes support backup to a USB attached drive and many do this trick with a networked share. But some drives support only attached drive backup."

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