It is given the next problem. Implement astorage system  which can allow 60Tb  data, which can be extensible,  fit in a rack and to be fault tolerant?

The solution consists of a series of blocks connected to each other. So:

• One block consist in :

1. Switch Gigabit (1U )
2. Enclosure AOE ( 15 HDD SATA 1TB each ) (3U)
3. Controler (1U)

• 1 Rack 0f 48U which will consist of 5 blockuri + UPS

Hardware costs:


6 * Switch Gbic 24 porturi (480$) = 2880$
5 * Enclosure AOE (4000$) = 20000$
5 * Controller (1000$) = 5000$
75 * Harddisk SATA 1 Tb (400$) = 30000$

TOTAL 57880$

Software solution:

Each controller takes care of one enclosure AOE. Each enclosure will have hard drives in RAID 5. Thus on each enclosure it is obtain a capacity of 14 TB of data. Set of blocks can be arranged in RAID  (stripping) to obtain a total capacity of 70Tb. But any failure of controller compromises the entire system. (Single point of failure). Each controller is exporting the file system using vlbade and ‘controller of controllers’ performs RAID 5 level blocks.

For full redundancy blocks are organized in RAID 5 capacity (56 TB)

That means a cost of $ 1,000 / Tb redundant.

Note 1: Calculation was done in March 2007. Meanwhile the prices of harddisks 1TB has fallen.

Note 2: We have not included all the costs of implementation. And how the implementation is done, makes the difference between a successful solution or a bad one.