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Freddy2003
2 Bronze

Saving power: Pulling (Temporarily) unused disks from DAE's???

Hi All,

Our company is trying to save power by switching off as much equipment as possible...

Now the idea has surfaced to switch off complete DAE's in our Clarion CX3-380's that are (currently) not in use, until we need them again.

I understand the DAE's are configured in loops on the Clariion's, so we can't simply switch off the power completely to the unused DAE (As this would break the loop, right?)

The unused DAE's have no RAIDGROUPS configured and the disks are in UNBOUND state.

My idea is to pull 14 of the 15 disks (Keeping a hotspare running), thus reducing the power-need of that particular DAE. This way the loop would stay intact and we could insert the disks back whenever we need them again.

My questions:

1) Is this possible without causing any problems, as the SAN has 'seen' the disks and now they are gone?

2) I assume plugging the disks back when needed, can be done live, whilst everything keeps running?

I guess best would be if EMC made a nice FLARE code (hint, hint ) for all Clariion's that doesn't SPIN the disks (FC and SATA) until they are bound in a RAIDGROUP, but I figure that won't happen any time soon

Hope you guys can help us with these questions.

Thanks in advance!

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12 Replies
Avi3
3 Silver

Re: Saving power: Pulling (Temporarily) unused disks from DAE's???

Hi,

CLARiiON already has such a feature called Disk Spindown which will spin down (qualified) drives if they are not bound in a RAID group. It also spins down drives which are not actively used by any application (in other words, drives with LUNs bound on them will also spin down due to inactivity).

This is available with FLARE R29 code and as a consequence this feature is available for CX4 arrays only. See "An Introduction to EMC CLARiiON CX4 Disk-Drive Spin Down Technology — Applied Technology" whitepaper on Powerlink for more details.

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Freddy2003
2 Bronze

Re: Saving power: Pulling (Temporarily) unused disks from DAE's???

Hi Avi,

I know that the CX4 line has Spin down (But only for SATA) and we will be using that feature on our CX4 SAN as well...

The question was for our CX3-380 series however...

Can we reduce the power of unused DAE's?

Why keep FC and SATA disks spinning if they really don't need to spin?

This would save customers a gigantic amount of money (Think of power, cooling but also the life expectancy of a disk) and would give EMC a great edge over competitors!

Additional benefit for EMC & customers would be less disk replacements, as unused disks would not be spinning and are thus less likely to break down! (This saves repair runs & downtime)

Message was edited by: Fredster

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Avi3
3 Silver

Re: Saving power: Pulling (Temporarily) unused disks from DAE's???

I understand your point.

If you pull out unused disks from the array, you will see an "E" icon for the 'missing' disks, but this will not cause any problems in data access to other LUNs in the array.

Freddy2003
2 Bronze

Re: Saving power: Pulling (Temporarily) unused disks from DAE's???

Hi Avi,

Thanks for your answer!

What is the chance that EMC would make a SPIN DOWN algorithm in a new FLARE code (Or some loose extension one could load extra)???

This would give EMC a nice & green ECO friendly edge over competitors (Saving the planet and some money for customers etc etc)

This new extension should ofcourse be made for all current types of SANs (CX series) and should be able to not spin up unbound disks (Both FC & SATA)...

Is there a way for customers to get feature requests like this to EMC engineers?

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Freddy2003
2 Bronze

Re: Saving power: Pulling (Temporarily) unused disks from DAE's???

Hi,

Another question:

Would a NaviCli CRU_ON_OFF procedure SPIN DOWN a disk???

Thanks!

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Avi3
3 Silver

Re: Saving power: Pulling (Temporarily) unused disks from DAE's???

You are in the right forum to point out these issues. This forum is monitored by EMC engineers and managers. However, the final implementation and inclusion of features such as these will depend on resource availability and priorities assigned to other such functionalities. But rest assured that your case will be forwarded to the appropriate people.

kelleg
4 Ruthenium

Re: Saving power: Pulling (Temporarily) unused disks from DAE's???

the cru_on_off will not spin down the disk and is not really to be used except in emergencies - you can cause a data loss if not careful.

glen

Freddy2003
2 Bronze

Re: Saving power: Pulling (Temporarily) unused disks from DAE's???

Hi Kelleg,

I thought it wouldn't SPIN DOWN the disks indeed

I realise also it is a very dangerous command to use and it is very easy to shutdown the wrong disk, but I do appreciate the warning

I do hope however, some EMC engineers can pick up this SPIN DOWN unused disks idea.

We have several DAE's out of use on our primary site, which means they are also out of use on our secondary site.

I am obviously not sure how much power it would save exactly per disk (or DAE) in a shutdown state, but for instance:

A CX4-120 (Completely filled with 600 GB FC 15k3 disks) costs well over 8000 euro's a year to run (Calculating with 0,15 eurocent/KWh and 50% DCE). Switching off one or more DAE's until needed could easilly save hundreds of euro's a year...

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kelleg
4 Ruthenium

Re: Saving power: Pulling (Temporarily) unused disks from DAE's???

As Avi said, there are quite a few EMC engineering managers that watch these forums.

glen

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