840 EVO 250gbx4 LSI 9266 4i seems slow?

bpgt64

n00b
Joined
Dec 11, 2013
Messages
4
Settings used;
Write through cache
no read ahead
direct write to drive

Tried a variety of striping, I am under-provisioning the drives, and still getting sub 1.2GB/s performance on writes. I know it shouldn't necessarily be additive, but still not getting what should I think should be right...~1.5gb/s-1.8
 

bpgt64

n00b
Joined
Dec 11, 2013
Messages
4
The test is Dxtory's benchmark, it writes a very large file to disk. ~10GBs
 

drescherjm

[H]F Junkie
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Nov 19, 2008
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14,927
Write back does open a chance of some data loss since the data is buffered in the cards 1GB of cache. If you lost power with data in still the cache your array would have some corruption that is if you do not have the BBU module.

I asked you to enable that because I thought the problem was due to too small writes. I mean when you raid0 whatever block size you are writing gets divided amongst the drives in the array. And since SSDs do not read or write small blocks at anywhere near 500MB/s you can see much lower performance then expected because all drives in the array are doing smaller writes. The cache fixes that by buffering the writes and flushing bigger blocks at a time.
 
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Old Hippie

Supreme [H]ardness
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Oct 31, 2005
Messages
6,013
You won't get great performance they would be capable of without the FastPath option.;)
 
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