March 7, 201214 yr I'm trying to vacate a drive that's red balled (so it's being computed) to another internal drive. It's going pretty slow... I'm wondering if it would be faster to move all the files to the cache drive instead and then move it to the other drive on the array... Right now I'm getting a measly15-15MB/s internal to internal... Jim
March 7, 201214 yr I'm trying to vacate a drive that's red balled (so it's being computed) to another internal drive. It's going pretty slow... I'm wondering if it would be faster to move all the files to the cache drive instead and then move it to the other drive on the array... Right now I'm getting a measly15-15MB/s internal to internal... Jim If you have room on the cache drive, it might be slightly faster... but you'll still be limited to approx 25-30 MB/s copying from the cache drive to the protected array. Since you are simulating the contents, ALL the drives are being read, so you are at the limit of the data bus. IF you can copy from the simulated drive to the cache drive at 50MB/s and you copy 1TB that is 20 seconds per GB, or 20,000 seconds. If you can then write at 25MB/s to the protected array that is 40 Seconds per GB, or 40,000 seconds. Total = 60,000 seconds or 16.6 hours. At 15MB/s, doing it directly from the simulated disk to another protected disk = 66.6 Seconds per GB, or 66,666 seconds = 18.5 hours. The time is not that much different in the long run... and I made up the theoretical speeds. If writing or reading from the cache drive is a bit slower, then the times will be nearly identical., Joe L.
March 7, 201214 yr Author I think I might have to do atest! :-) At least copying to the cache drive will allow me to remove the bad drive sooner (In theory) then when the array is protected again.. I can copy back at my leisure. My objectives are two-fold: 1. get the disk out of the array so I can test it as soon as I can.. 2. return the array to a protected state as soon as I can! My cache drive is only 1/3 the size of the protected drive so it might not matter as I would have to do it in stages! I'm almost done with my group move in MC. Then I can try some single file experiments to see if it is faster.. Jim
March 7, 201214 yr I'm almost done with my group move in MC. Then I can try some single file experiments to see if it is faster.. Jim I'm sure many will be curious to see the results of your experiments in copying speed.
March 7, 201214 yr Author File 1: 6341MB Crippled Array to Cache drive: 2:16 -> 46.6MB/s Cache drive back to crippled array (different real drive): 4:51 -> 21.8MB/s Total time 427 secs. for 14.8MB/s File 2: 6358MB Crippled array (calculated disk) to crippled array (real disk): 7:50 -> 13.5MB/s So adjusting for the small difference in file sizes.. File #1 would have taken 469secs. so I would have saved 42secs... so for a 1 TB drive the difference is 1234 minutes vs 1126 minutes. for a savings of 108 minutes per TB. Is it worth it? maybe not since the first option requires two copy steps.. that may take time to... But YMMV.... I wonder what the cache to a protected array (healthy array) time would be?? I guess I'll have to wait for that! Jim
March 8, 201214 yr File 1: 6341MB Crippled Array to Cache drive: 2:16 -> 46.6MB/s Cache drive back to crippled array (different real drive): 4:51 -> 21.8MB/s Total time 427 secs. for 14.8MB/s File 2: 6358MB Crippled array (calculated disk) to crippled array (real disk): 7:50 -> 13.5MB/s So adjusting for the small difference in file sizes.. File #1 would have taken 469secs. so I would have saved 42secs... so for a 1 TB drive the difference is 1234 minutes vs 1126 minutes. for a savings of 108 minutes per TB. Is it worth it? maybe not since the first option requires two copy steps.. that may take time to... But YMMV.... I wonder what the cache to a protected array (healthy array) time would be?? I guess I'll have to wait for that! Jim Looks like my guesses were not that far off.
March 8, 201214 yr Author Ok.. what gives.. This morning as I resumed my file copy (same MC session) I'm now getting 17-18MB/s!! why was it ~13MB/s yesterday and today it's ~18MB/s! There's no other activity (that I know of) yesterday or today.... strange! Well at least it went up Jim
March 8, 201214 yr Copy to the cache, remove the drive and rebuild parity and then run the mover and copy back to the array.
March 8, 201214 yr Author Unfortunately.. My cache drive is only 1/3 the size of the disk being replaced. So I have to get it down below that first!
March 8, 201214 yr Ok.. what gives.. This morning as I resumed my file copy (same MC session) I'm now getting 17-18MB/s!! why was it ~13MB/s yesterday and today it's ~18MB/s! There's no other activity (that I know of) yesterday or today.... strange! Well at least it went up Jim outer cylinders of the disks can be accessed more quickly than inner cylinders. It is quite normal for access speeds of disks to vary.
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