March 16, 201016 yr Brief background: Testing out latest unraid with a 3-drive array, 3x 500gb 7200rpm drives (few years old), pci-e MB sata connectors. Like what I see; 25-30 mb/sec write and read. My use case is mostly large media files, so typically I'll have a single drive spun up and operating. So now I'm looking at buying/building bigger, and I found these drives: http://www.newegg.com/Product/Product.aspx?Item=N82E16822136456 http://www.newegg.com/Product/Product.aspx?Item=N82E16822152202 They seem to be the only 2tb drives that are not suffering dramatically high failure rates. So I have some questions: 1) The Caviar Black has "dual processors" and is reported to perform on par (or better) with current generation SATA-3 drives. But it's also ~2x the cost. Is this really worthwhile? How much difference, in MB/sec, would I expect to see? 2) If the parity drive is super fast, but the data drive is slower, am I then gated by the slower data drive's max performance? (assuming no cache drive) 3) If you're only using PCI-E, where is the bottleneck that limits perf to ~30mb/sec read/write? Is it still that bus?
March 16, 201016 yr 2) If the parity drive is super fast, but the data drive is slower, am I then gated by the slower data drive's max performance? (assuming no cache drive)Yes... you are limited by the rotational speed of the SLOWEST disk involved, regardless of if it is the parity disk or the data disk. 3) If you're only using PCI-E, where is the bottleneck that limits perf to ~30mb/sec read/write? Is it still that bus? The write speeds are now up to 40 to 45 MB/s writing to the array and reading is much faster at 60-80MB/s with good networking. The write speed bottleneck is due to the rotation of the disk platter between reads, writes, and subsequent reads. See this post: http://lime-technology.com/forum/index.php?topic=4390.msg40684;topicseen#msg40684
March 16, 201016 yr Author Thanks for that. Does TLER cause issues with Unraid? Any suggestion as to what might cause read speed to be low -- identical to write speed, 25-30mb/sec? Can you point me to some links of people reporting their config and 40-45mb/sec write speeds? Searched, couldn't find anything about this. I'd like to take a look at the drives they are using, in particular.
March 16, 201016 yr Thanks for that. Does TLER cause issues with Unraid? Any suggestion as to what might cause read speed to be low -- identical to write speed, 25-30mb/sec? Can you point me to some links of people reporting their config and 40-45mb/sec write speeds? Searched, couldn't find anything about this. I'd like to take a look at the drives they are using, in particular. Here is one: http://lime-technology.com/forum/index.php?topic=5496.msg51190#msg51190
May 2, 201016 yr I realize this is a older thread but I have been missing in action due to work.. I have several of these drives & they work great. Have had zero problems & they are retail drives so the packaging for shipping is better than most drives sent from the Egg. http://www.newegg.com/Product/Product.aspx?Item=N82E16822145276 Hope this still helps.. Phil
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