[mythtv-users] Why RAID 5 stops working in 2009

Steve Heistand steve at heistand.org
Sat Oct 25 00:03:29 UTC 2008

Thomas Fjellstrom <tfjellstrom at shaw.ca>, said on Fri Oct 24, 2008 [05:58:46 PM]:
} On Friday 24 October 2008, Steve Heistand wrote:
} > } >
} > } My understanding is that raid5 and raid6 write performance is sensitive
} > } to the size of writes compared to the stripe size. Assuming that is true
} > } what would be the optimal stripe size for a mythtv raid5 for recording
} > } HDTV? Can the size of mythtv read and write sizes be adjusted to improve
} > } performance for a storage group on a raid5 array?
} >
} > true, but this falls under the hurry up and wait category.
} > even the worst performaning raid is faster then hdtv needs.
} > bad raids give 20M/sec, uber HD signal needs about 5M/s.
} Wow, 20M? My laptop's single pata 5400rpm disk gives me 40 :o I get 200-300 
} from my new raid5 (4x640 sataII).

its not doing the md5 sums while its writting on a really slow cpu now is it :)
that is the really low end at 20M/s, good consumer hardware raids can do ~500M/s
we have some enterprise raid systems at work that can squeeze 2-3G/s without any

"Why is it so hot inside this handbasket?"
Steve Heistand
steve at heistand.org

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