# Ultra Dense Thumper

I had an idea for a new product this morning while waiting for boiling water for my tea: A ultra dense packed Thumper. In a X4500 you can put 48 hard disks with 1 TB worth of storage per disks, giving you 48 TB of storage. An disclaimer at first: This is not an upcoming product as far as i´m aware of and it´s only a tought game on the basis of data sheets from the websites of the usual suspects. Okay, the casing of the X4500 has a width of 439 mm and a length of depth of 749,9 mm. Let´s assume we can´t use 10 mm of the length and 10 mm of the size. We keep the size of 4 rack units. Now let´s change a little piece of the equation: We will use 2,5 disks! A Samsung HM500LI has a width of 69,85 mm, a length of 100 mm and a height of 9,5 mm. The disks will plugged in from above like with the normal thumper. The small side will be parallel to the the front side to the casing. A 4 RU unit casing like the thumper has a height of 175 mm, the disk takes 100 mm. So we have 75 mm for the top and the bottom of the casing of the “Dense Thumper”, the “system controller” and a backplane. As 1 RU (44,5m) dual socket is normal, it should be not problem to integrate the system beneath the harddisks with plain standard technology. Let´s further assume that every harddisk get´s 1,5mm additional space in the direction of the airflow and 0.5mm in the other orientation.So a disk takes 12,5mm in height and 70,85mm in width. Let´s further assume, that you need an 5 mm per disk for a simple slide-in holder (increasing the width …something like two miniature u-profiles sliding in each other) With such dimensions you would be able to hold 38 disks on the width of the “ultra dense thumper casing” and 9 disks on the length of the casing. This leads to a total amount of disks in the casing of 342 disks. A HM500LI has 500 GB per disk, thus such a “Dense Thumper” would give you 171 Terabyte (marketing ones) of storage on 4 rack units. The whole disks would take something aroung 900 watts of power. BTW: A staggered spin-up of all these disks looks really sensible … Connecting the all these disks to the system is a little bit tricky. But this should be solvable to. The is a chip called LSI LSISASx36. This is a 36-Port 3Gb/s SAS Expander. We use 4 connections for outside connections and 32 lanes for disk connection. Thus we have to connect 11 of this chips. This chips could connect to SAS controllers like the LSISAS1068E, an 8-Port PCI Express to 3Gb/s SAS Controller. This leads to the necessity of 6 of this controller as we can connect 2 expander to 1 controller chip. For this 6 Controller you would need 6 PCI Express busses. This should be solvable with a Opteron based system. I should write a mail to Andy …