Re: Linux MD RAID 5 Benchmarks Across (3 to 10) 300 Gigabyte Veliciraptors

[Justin Piszcz <jpiszcz@lucidpixels.com>]

On Wed, 11 Jun 2008, Justin Piszcz wrote:

>
>
> On Wed, 11 Jun 2008, Bill Davidsen wrote:
>
>> Justin Piszcz wrote:
>>> First, the original benchmarks with 6-SATA drives with fixed formatting, 
>>> using
>>> right justification and the same decimal point precision throughout:
>>> http://home.comcast.net/~jpiszcz/20080607/raid-benchmarks-decimal-fix-and-right-justified/disks.html 
>>> Now for for veliciraptors! Ever wonder what kind of speed is possible with
>>> 3 disk, 4,5,6,7,8,9,10-disk RAID5s? I ran a loop to find out, each run is
>>> executed three times and the average is taken of all three runs per each 
>>> RAID5 disk set.
>>> 
>>> In short? The 965 no longer does justice with faster drives, a new chipset
>>> and motherboard are needed. After reading or writing to 4-5 veliciraptors
>>> it saturates the bus/965 chipset.
>> 
>> This is very interesting, but a 16GB chunk size bears no relationship to 
>> anything I would run in the real world, and I suspect most people are in 
>> the same category.
>
> I based my bonnie++ test on:
> http://everything2.org/?node_id=1479435
>
> So I could compare to his results.
>
> I use a 1024k (1MiB) with 16384 stripe, this offered the best overall 
> read/write/rewrite performance AFAIK.

1024k chunk size (raid5 chunk size)
echo 16384 > stripe_cache_size