GREEN Storage Service

An overview of the range of memory options offered by the IT Services of ETH Zurich.

In this post, the System Services department (ITS SD) compares the power consumption of central disk systems with tape storage. Decentralized storage in the departments may actually consume more electric power per TB, since we are often dealing in this context with old servers that can be switched off after a successful data migration.

Disk systems

Within the scope of a full cost accounting in 2013, we determined the power consumption of all components participating in the Storwize V7000 Gen1 memory (SAN block storage):

  1. from the device information
  2. repeated measurement with current pliers in “normal operation” and determination of the mean value

The result was values of approx. 20 W/TB for the disk systems.

Tape solutions

Power measurements on the TS3500 tape library in the HPV showed overall values of 1700 W for “normal operation”. This corresponded in 2013-2014 to a power consumption of approx. 0.3 W/TB. With the new drives and the associated increase of capacity from 4 to 7 TB per cartridge, this value falls to under 0.2 W/TB. So a value of 0.4 W/TB can be assumed since the data is stored on tape at both locations (RZ and HPV).

LTS – our “green storage island”

The LTS service available since 2014 currently stores 0.7 PB of valuable data on 2 tapes. For the retention of this 0.7 PB, e.g. for one year, we need 280W*24h*365 after the writing, amounting to about 2400 kWh. If this data had still remained on discs, it would have consumed about 1.2 105 kWh – about 50 times the amount.

Flash memory systems

IT Services has also used 100% flash memory systems in the block storage area since the onset of 2015. Unfortunately, there are currently no measured values of their power consumption on hand. Based on the manufacturer’s information, we assume values of around 3.5 W/TB for the power consumption of these flash memories. The low power consumption per TB of stored data is achieved through state-of-the-art software for data reduction, among other things. We will report again as soon as we are able to store sufficiently large quantities of data in this storage area and then measure the power consumption in “normal operations”.


  • Data Storage and Storage Services (ITS page)

Contact & text

IT Services, System Services (ITS SD), Dr. Tilo Steiger (Group Manager, Storage)


(External translation service)

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