August 5, 201411 yr Now that WD 6TB drives have reached the UK (£204 inc delivery), and I was going to buy another couple of 4TB drives, i'm thinking about a couple of these bigger WD Reds. One would be for data and the other for parity, freeing up a couple of smaller 4TB drives as backup. But ... the WD spins at 5400rpm whereas the current data drives are Seagate nas drives which spin at 5900rpm. Any potential problem there with parity running slower than the rest of the drives? Ideally i'd like a Seagate 6TB at 5900 ... not over here yet. And what's the process for swapping over to an increase in parity?
August 5, 201411 yr A 6TB parity will actually be faster than the Seagate ... well, at least in one respect => It will have a higher transfer rate, since it's got a 20% higher areal density. That means 20% more data is transferred per revolution ... so the 5400rpm of the 6TB Red is, for data transfer purposes, equivalent to 6480rpm with a 1TB/platter drive. The Seagate will still have a slightly faster seek time, but not enough to matter. And that only impacts multiple simultaneous writes to the array (when more than one system is accessing it at the same time to write data) Your parity checks will run at the speed of the Seagate drives, since the Red is actually faster in sustained data rate (although after the checks pass the 4TB point, they'll speed up to the Red's speed). Bottom line: Don't worry about it ... everything will be just fine
August 5, 201411 yr And what's the process for swapping over to an increase in parity? Same as for any other drive. - Do a parity check and confirm all is well (no sync errors; no disk errors). - Shut down the array and assign the new drive as parity. - Restart the array ... and wait for the parity rebuild to complete (this will take a LONG time). - When it's done, it's a good idea to run a parity check to confirm all went well.
August 5, 201411 yr Author So ... seems i'm good to go WD then. Seens the best use for my cash instead of just buying in a couple of 4TB Seagates again, even though they've come diwn in price!
August 6, 201411 yr I'd agree. The difference in the cost/TB is nominal, and moving to 6TB drives is the way to go if you're expanding your array. Certainly all I'll be buying from here on out [until even larger drives are available ]
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