關於儲存設備容量需求的計算問題
 

各位學長：

底下這題是個計算題：

An application uses 20, 10 GB devices. A pointer-based full volume replica of the application is required every 6 hours. Each replica will be kept for 24 hours. The data changes by 10% every 4 hours.
How many replica devices are required?

我是這樣想的：

(10*20/6*24*(1.1)^6)/10=141.724, ---142

可是答案是80。不曉得哪裡錯了，再請學長們指導，萬分感謝!!

A pointer-based full volume replica of the application is required every 6 hours.
重點只在這一句，100%複製。

24/6 * 20=80

打完收工。

學長真是了不起，豁然開朗，心情愉快!!

能不能再請教一題？感謝!!

A department within an organization requires 200 GB of storage for their business application. The production LUN is RAID 1+0 protected and has a local and remote replica. The local replica is on a RAID 1 LUN and the remote replica is on a five-disk RAID 5 LUN.

If the cost per GB of storage is $2.00, what is the chargeback cost to the department for application storage?

答案是$2100，完全無法理解><

RAID 0+1 -> (100+100)x2 = 400G
RAID 1 -> 200x2 = 400G
RAID 5 -> 200x5/(5-1) = 250G

(400+400+250)x2= 2100