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How can this be?


kenoka

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A few days ago, I went through a fair bit of trauma with my unRAID system. It revolved around the Supermicro controller card that I'd added, which caused repeated parity checks and reboots. After removing the card for RMA service, everything has been running fine. Too fine, if anything. Before I added the additional card, writes to this server were going at about 25 MB/s, which I was okay with.

 

Ever since I had to delete a drive and rebuild parity, writes have been relatively blistering at about 35-40 MB/s. I'm at a loss to explain this. Parity looks to be valid, and nothing else has changed.

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But that's the thing: the only change has been moving one drive from the Supermicro card to the eSATA port on my motherboard. Otherwise, all other drives are on the motherboard ports, which are on the southbridge's channel. And the change in transfer rates dates back to BEFORE I added the Supermicro card.

 

 

 

 

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No cache drive?  Is parity actually being updated when you write to the array?  How much RAM do you have?  That does seem exceedingly fast (w/o a cache drive, at least).

 

Yes, parity is being updated. If I update my web interface, I can watch it being written to. I have 4GB of RAM. I had 6GB in there, but pulled two sticks to upgrade another computer which only had 512MB. It made a world of difference, as I had upgraded it from Windows XP to the latest Ubuntu.

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  • 4 weeks later...

I think I've figured this out. The drives I initially installed as data drives were Western Digital 1.5TB EADS. Those all worked at about 25MB/s. Subsequent drives were all 7200rpm drives, and I think it's these that are getting the higher 35-40MB/s. I'm guessing this newer 5900rpm drive can get good speeds when paired with older 7200rpm drives, and leaves the older EADS behind.

 

It would be interesting to compare to a newer EARS. What speeds are people seeing with a 2TB EARS as parity?

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I think I've figured this out. The drives I initially installed as data drives were Western Digital 1.5TB EADS. Those all worked at about 25MB/s. Subsequent drives were all 7200rpm drives, and I think it's these that are getting the higher 35-40MB/s. I'm guessing this newer 5900rpm drive can get good speeds when paired with older 7200rpm drives, and leaves the older EADS behind.

 

It would be interesting to compare to a newer EARS. What speeds are people seeing with a 2TB EARS as parity?

 

I have a new 2Tb EARS as parity.

 

I am usually transferring files from my htpc external hard drive (Samsung 1.5Tb 5400 rpm)

 

My data discs are the (not-recommended by the community) Samsung 2Tb f4 5400 rpm

 

Small files (~500MB) transfer to the array at ~ 28 to 31 MB/s

 

Large files (>4GB) transfer to the array at ~ 20 to 21 MB/s

 

 

I have an old 7200 rpm Maxtor drive mounted with SNAP (so no parity) and I have seen 45 to 55 MB/s transfers.

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