On Thu, 2013-07-04 at 20:12 -0500, Stan Hoeppner wrote: > 1. You'll need to use partitions underneath md because the drives will > all be slightly difference capacity. Well it doesn't have to be partitions... you can simply manually specify a somewhat smaller size for the RAID... but of course one should leave some gap. I'll probably doe it via partitions, though ;) btw: It was interesting to see,... that all 3 different drives (from WD, HGST, Seagate)... exported _exactly_ the same amount of space. > You'll need to identify the > capacity of the smallest drive and create partitions a few MiB smaller > than this on all drives. This should assure that any replacement drive > which is slightly smaller will be usable in the array. Sure... > Screwing around with all of this is a PITA. When I build arrays I use > identical drives and put identical spares in storage. I don't leave > hot/warm/cold spares in the chassis. Well but that's another field of questions ;) > This simply degrades performance. Why should it? If the spare is unused? > Hot swap was invented for a reason. Some folks prefer online spares an > unattended auto rebuild. Not every time a drive is kicked is a rebuild > required. I wanna look things over before I start a rebuild. I also think that for my personal home use case hot/warm/cold spares won't be of much use... but if you run a big data centre things look different... and hot spares are not replaced by hot swap ;) > 2. HGST is a brand created due to Western Digital's acquisition of > Hitachi Data System's disk drive unit. Sure... but I think they still use their own technology/firmware... at least for now? > The drives are Hitachi's final > production units relabeled with a different name and serial number. > Three years from now when that HGST drive fails, Western Digital will > replace it with a Western Digital produced drive. Sure about that? Wasn't there some agreement that HGST belongs to WD but produces independently...? Anyway... that's off topic... for now at least the disks are not identical (which was my goal)... and Toshiba got something from the WD/HGST trade and already announced a 3.5" enterprise disk out of that. > IMO the practical disadvantages of using dissimilar drives outweighs the > theoretical benefits. So... which are the practical disadvantages? Cheers, Chris.
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