Raid 5 vs 0+1 Comparison?

[Lukano]

My employer is currently working on a billing system transition and with the software came a new provisioning system.

We've been having latency and I/O issues for the past 6 weeks or so, and they've been plugging away at the software core trying to solve those issues.

I discovered today that one of the major changes was a transition to newer/bigger/faster drives and from the current RAID 5 array to a RAID 0+1.

Now I'm tentatively comfortable with RAID and the benefits/disadvantages to each array type. I understand that 0+1 has a higher cost vs. storage ratio - which really isn't an issue in this case.

On the same token, I also understand that 0+1 is ond of the best choices for sheer I/O - but what sort of performance gain can really be expected over the current RAID 5 situation?

I'm hardly fully versed on the situation at hand, being in a different department - but it's my understanding that the current SAN arrangement for the database is the root of the problem, and although they swear the 0+1 will fix all of our woes (and trust me, there's a literal 3 second que time on each query, which means when you're doing point-of-sale you''re looking at a tri-fold increase on processing time for each order).

So... RAID 5 vs 0+1 ? Really all it's cut out to be?

 

[DougLite]

For writes, 0+1 > 5.
For reads, it depends on the load. For linear straight through transfers, the larger number of striped drives on 5 increases throughput. For random multi user loads, being able to service 2 concurrent reads (one with each mirror set) allows 0+1 to pull ahead.

Generally, I only recommend RAID-5 for situations where the capacity/spindle ratio is the utmost concern. When performance is a concern, 0+1 is generally a better choice.

There may be other I/O bottlenecks in this system - perhaps newer faster drives are in order as well?