topic How does nimble calculate min. usable capacity for the arrays? in Array Performance and Data Protection https://community.hpe.com/t5/array-performance-and-data/how-does-nimble-calculate-min-usable-capacity-for-the-arrays/m-p/6985151#M821 <HTML><HEAD></HEAD><BODY><P>I'm just curious if anyone knows how the minimum usable capacity is calculated for an array. For example, on their website, a 72TB(12x6TB) raw disk capacity array's minimum usable capacity is 50TB. I know Nimble uses RAID-3P which is triple parity with no dedicated spare, I feel like this way the minimum capacity should be bigger than RAID6 with spare which has 72-(6x3)=54TB minimum capacity.</P></BODY></HTML> Wed, 16 Dec 2015 20:28:32 GMT jliu79 2015-12-16T20:28:32Z How does nimble calculate min. usable capacity for the arrays? https://community.hpe.com/t5/array-performance-and-data/how-does-nimble-calculate-min-usable-capacity-for-the-arrays/m-p/6985151#M821 <HTML><HEAD></HEAD><BODY><P>I'm just curious if anyone knows how the minimum usable capacity is calculated for an array. For example, on their website, a 72TB(12x6TB) raw disk capacity array's minimum usable capacity is 50TB. I know Nimble uses RAID-3P which is triple parity with no dedicated spare, I feel like this way the minimum capacity should be bigger than RAID6 with spare which has 72-(6x3)=54TB minimum capacity.</P></BODY></HTML> Wed, 16 Dec 2015 20:28:32 GMT https://community.hpe.com/t5/array-performance-and-data/how-does-nimble-calculate-min-usable-capacity-for-the-arrays/m-p/6985151#M821 jliu79 2015-12-16T20:28:32Z Re: How does nimble calculate min. usable capacity for the arrays? https://community.hpe.com/t5/array-performance-and-data/how-does-nimble-calculate-min-usable-capacity-for-the-arrays/m-p/6985152#M822 <HTML><HEAD></HEAD><BODY><P>Jason- Good question.&nbsp; Nimble's minimum usable capacity would be RAW storage capacity minus RAID overhead (triple parity/three drives) as you stated.&nbsp; Then there is some small system overhead, which accounts for the other 4TB "missing" capacity in your calculation, using the 72TB example above.&nbsp; As<SPAN style="font-size: 13.3333px; line-height: 1.5em;"> an example </SPAN><SPAN style="font-size: 13.3333px; line-height: 1.5em;">of miscellaneous system data that can't be counted as capacity</SPAN><SPAN style="font-size: 13.3333px; line-height: 1.5em;">,</SPAN><SPAN style="font-size: 13.3333px; line-height: 1.5em;"> t</SPAN><SPAN style="font-size: 10pt; line-height: 1.5em;">here are multiple redundant copies of the Nimble OS.</SPAN></P></BODY></HTML> Wed, 16 Dec 2015 21:35:25 GMT https://community.hpe.com/t5/array-performance-and-data/how-does-nimble-calculate-min-usable-capacity-for-the-arrays/m-p/6985152#M822 2015-12-16T21:35:25Z Re: How does nimble calculate min. usable capacity for the arrays? https://community.hpe.com/t5/array-performance-and-data/how-does-nimble-calculate-min-usable-capacity-for-the-arrays/m-p/6985153#M823 <HTML><HEAD></HEAD><BODY><P>Thanks Ed for the explanation.</P></BODY></HTML> Thu, 17 Dec 2015 14:03:29 GMT https://community.hpe.com/t5/array-performance-and-data/how-does-nimble-calculate-min-usable-capacity-for-the-arrays/m-p/6985153#M823 jliu79 2015-12-17T14:03:29Z