July 27, 201312 yr I'm preparing to replace a failing 1TB drive in my array to a new 2TB drive, and am running preclear on the drive first. For the preread i'm getting about 80MB/s. Does that seem about right or a little slow?
July 27, 201312 yr I'm preparing to replace a failing 1TB drive in my array to a new 2TB drive, and am running preclear on the drive first. For the preread i'm getting about 80MB/s. Does that seem about right or a little slow? It is about perfect. Most drives hit between 80 and 100MB/s on the outer cylinders and then between 50 - 80 MB/s on the inner cylinders.
July 27, 201312 yr Agree it's just about right for many 2TB drives ... but the newer 1TB/platter drives run appreciably faster. I just did a new WD 2TB EZRX unit and had these results: == Using :Read block size = 8225280 Bytes == Last Cycle's Pre Read Time : 5:12:42 (106 MB/s) == Last Cycle's Zeroing time : 4:24:59 (125 MB/s) == Last Cycle's Post Read Time : 9:43:18 (57 MB/s) == Last Cycle's Total Time : 19:21:58 == == Total Elapsed Time 19:21:58 The pre-read started off well over 140MB/s ... and even with the slowdown as it moved inwards, still averaged 106MB/s for the entire drive. Your drive is doing just fine -- I suspect it's a 667GB/platter unit or possibly even an older 500GB/platter unit. But I've definitely been impressed by the new 1TB/platter units. I just built a new small UnRAID server for a friend using several of the 2TB EZRX drives, and it easily maxes out a GB network with reads (~ 120GB/s); and does a parity check in just over 5 hours. By the way Joe => could you outline just what the post-read does that takes so much time?? I assume you're just "thrashing the daylights" out of the drive by doing the post-read in a somewhat random order to ensure a VERY good exercise of the drive ... seeks are, after all, in relative terms very slow compared to the actual data transfer. A related question: Is anything written to the disk after the post-read starts? i.e. if you simply shutdown the system via the Web GUI once the post-read started (thus aborting the script), would the drive be ready to use? I do NOT have any plans to EVER do that ... I'm just curious if the actual pre-clear is completed at that point (as the 10 indicated "Done" steps would imply it is).
July 28, 201312 yr Author Thanks guys, I'm halfway through on the first of 3 cycles, and the zero'ing (stage 2) is writing at ~115, so things are looking good. Just hate that it takes so damn long!.
July 28, 201312 yr Thanks guys, I'm halfway through on the first of 3 cycles, and the zero'ing (stage 2) is writing at ~115, so things are looking good. Just hate that it takes so damn long!. Just remember that the post-read takes about as long as the SUM of the pre-read and zeroing times ... and you also told it to do 3 cycles !! ... so it's going to be at least a couple more days.
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