Did you imagine how much electricity we could save if we could stop the harddisk from spinning when not in use. Oh you might say, what big deal, how can one hard disk make a difference. For people who dont know much about data and storage, let me tell you that a even a small bank in India would be utilizing the services of 4000 disks for its banking data.
Bigger banks need more disks and more and more for backups, replication (disaster recovery) etc. Its very common for banks and telcos to have atleast 5 PB (petabyte) of data. I’m considering the least, the maximum I have heard is 20 PB.
Quick Info : 1 PB = 1000 Terabyte = 1000000 GB
Lets assume the average disk size to be 300 GB, then 1 PB/ 300 = 16000 disks approx.
These 16,000 disks keep spinning idly, consuming a lot of power. So why dont we buy as we grow, does any body need 1 PB or more. Yes and No..! Storage cannot be bought in the last minute, it has to be brought well in advance and allocated to each server specifically. The data is critical so the storage has to be mirrored, replicated etc. Basically a lot of preparation.
So companies normally buy storage and pre-allocate it to the servers, as per the application growth rates.
Say if the application is currenlty occupying a 50 GB of space, and is expected to grow to 300 GB by next year, then the IT manager buys disks for 500 GB just to be on the safer side. So when just one HDD is utilized, others keep spinning and contributing to power consumption. Thin provisioning helps you allocate the storage space prior to the adding disks. For example you can allocate 500 GB of space, and still have only 1 OR 2 disks. And when the requirement arises, you simply add disks to the pool.
This saves a lot of energy, as few disks are required in the storage system.
Another technology is the ability to selective hard disks or RAID groups in a a system, when not in use.
A few companies I know who have implemented thin provisioning are HITACHI, 3PAR, COMPELLENT etc.
So people, go thin to save energy, I hope you know that we only have a few watts left.. 