This post is more than 5 years old
5.7K Posts
1
7683
10k drives versus 15k drives: rotational speed issues
Reading about the VNX machines I came accross the following about disk sizes, rotational speeds and platter sizes in inches:
in document "h8514-vnx-series-ss.pdf" I read that the 10k drives are 2.5 inches and the 15k drives 3.5 inches. I always thought that the faster a disk rotates, the smaller a platter should be because of the speed the edges of a platter reach. In fact: I opened a few 15k drives that were broken and I noticed that indeed the 15k drives contain the smaller platters and the 10k drives contain the "larger" 3.5 inch platters.
So why is this reverse with the VNX ? Or is this simply a typo ?
Can someone explain to me why the slower drives are also smaller ?
gprdawson
24 Posts
0
January 21st, 2011 03:00
I think the 2.5" drives are slower due to packaging issues.
It might not be possible to pack a faster, more powerful, motor and handle its cooling requirements using the 2.5" drive form factor.
RRR
5.7K Posts
0
January 21st, 2011 04:00
I don't mean the whole drive casing, just the platters
jps00
392 Posts
0
January 21st, 2011 04:00
The 2.5" drives have the same IOPs as a 3.5" drive, but slightly less average bandwidth for the same speed. The lower bandwidth is due to the geometry of the smaller platter and the linear access of mechanical hard drives.
Actually, because of the VNX's SAS backend, you will need completely new DAEs for VNX. Despite having the same name, they are differernt beasts. That is, unlike the last several generations of CLARiiON where you could 're-purpose' DAEs from the previous generation, you must buy new.
The new DAE's for the 5000/7000-series VNXs are as follows:
15 drive (3.5" FF) 3U 6G SAS DAE will show as DAE6S in Unisphere
25 drive (2.5" FF) 2U 6G SAS DAE will show as DAE5S in Unisphere
RRR, I expect that you and Dynamox both have 7500s on-order?
Spril1967
34 Posts
0
January 21st, 2011 04:00
There are also pictures of alle type of disk's here
http://www.qdpma.com/Storage/StorageConfig_A.html
Kenneth
RRR
5.7K Posts
0
January 21st, 2011 04:00
Ahhhh.... I see where I'm going in the wrong direction: the pdf states "form factor", so that's the drive casing ! So the VNX really can hold larger drive casings as well as smaller ? Do we need different DAE's to accomplish this ?
RRR
5.7K Posts
0
January 21st, 2011 05:00
Sure, in fact 4 !
Hahaha.
But to complete this thread: it's all clear to me now. Time for the weekend.
RRR
5.7K Posts
1
January 21st, 2011 06:00
So the DAE to hold the smaller and new form factor drives will be the DAE5S and the one with the 3.5 inch will be the DAE6S. Good to know.