Gregory Leblanc wrote:
>
> I don't have anything that caliber to compare against, so I can't really
> say. Should I assume that you don't have Mika's RAID1 read balancing patch?
I have to admit I was ignorant of the patch (I had skimmed the archives,
but not well enough). Searched the archive further, found it, patched it
into 2.2.16-RAID.
However, how nervous should I be putting it on a production server?
Mika's note says 'experimental'. This is my main production server and I
don't have a development machine currently capable of testing RAID1 on
(and even then, the development machine can never get the same drubbing
as production).
That said, it looks like the patch has an impact (although I'm not
familiar with tiobench):
tiobench results before Mika's patch:
File Block Num Seq Read Rand Read Seq Write Rand
Write
Dir Size Size Thr Rate (CPU%) Rate (CPU%) Rate (CPU%) Rate
(CPU%)
------- ------ ------- --- ----------- ----------- -----------
-----------
. 1024 4096 1 11.73 7.35% 1.008 1.54% 10.63 11.2% 1.452
11.8%
. 1024 4096 2 12.65 7.78% 1.072 1.44% 10.15 10.5% 1.397
12.5%
. 1024 4096 4 12.95 8.08% 1.177 1.70% 9.671 9.95% 1.393
12.6%
. 1024 4096 8 12.79 8.45% 1.273 1.85% 9.344 9.89% 1.377
12.8%
tiobench results after Mika's patch:
File Block Num Seq Read Rand Read Seq Write Rand
Write
Dir Size Size Thr Rate (CPU%) Rate (CPU%) Rate (CPU%) Rate
(CPU%)
------- ------ ------- --- ----------- ----------- -----------
-----------
. 1024 4096 1 22.83 14.9% 1.035 0.86% 10.97 11.2% 1.416
13.5%
. 1024 4096 2 26.66 18.7% 1.263 1.21% 10.42 10.6% 1.395
11.6%
. 1024 4096 4 27.74 20.2% 1.349 1.20% 9.795 10.0% 1.395
12.2%
. 1024 4096 8 24.69 20.8% 1.475 1.46% 9.262 9.82% 1.388
12.0%
Thanks for the help.
Jeff Hill
> > I have to say the RAID-1 works very well in my crash tests, and that's
> > the most important thing.
>
> Yep! Although speed is the biggest reason that I can see for using Software
> RAID over hardware. Next comes price.
> Greg
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