Disk spin down option

[fujitsusiemens01]

Hi folks, can anyone answer the folowing question?

If the third party storage solution, connected to a V-series, natively supports "spindel spin down" as an energy saving mode, will this still work when connected to a V-series?

My gut feeling is "no", but I can not find anything describing why not.

Rgds,

Mark

[isaacs]

Hello Mark,

Your gut was right.  We don't support disk spin-down on the disks supporting LUNs that are used by the V-Series.  Spin Down could still be utilized for other data sets, just not the V-Series LUNs.

Thanks!

Dan Isaacs

V-Series

Product & Partner Engineer

isaacs@netapp.com

[fujitsusiemens01]

Hi Daniel,

Thanks for your fast response, but can you also explain why this is/can not be supported? What is the technical reason?

regards,

Mark

[radek_kubka]

Hi Mark,

To me it is just a common sense - when disks spin down it means the LUN on them actually disappears (until disks spin back up) & ONTAP has not been designed to properly handle disappearing storage space .

Regards,
Radek

[fujitsusiemens01]

So Radek, would you describe it as a flaw in Ontap which could be addressed in a newer version?

On the other hand, isn't it so that Ontap is communicating with the thirdparty controller which does understand disk spindown.

Let me put it differently....

The LUN disappearing as you put it would be the same as when the thirdparty storage was used independably as standard. However, it would seem that the thirdparty storage controller

is able to support spindle powerdown without hosts noticing the temporary "loss" of the LUNs to which they are connected. So if they can "spoof" the LUN "loss" to standard hosts, would/should this then

not also be possibe if the "host" were to be a v-series?

regards,

Mark

[radek_kubka]

So if they can "spoof" the LUN "loss" to standard hosts, would/should this then
not also be possibe if the "host" were to be a v-series?

I would love to see this "spoofing" in action. Arguably this may be good enough for a backup / archive server which may wait until disks actually spin up, but I can't imagine how this may work with a V-Series box which (not surprisingly) expects the data to be available straight away.

[niels]

Hi Marc,

the explanation is pretty simple (I hope).

The spin-down will most likely happen after a certain period of idle time on the LUNs, right? (I'm guessing as I'm not familiar with the specifics of spin-down).

Due to the way ONTAP and WAFL work, we are writing a consistency point to the disks/luns no later than every 10 seconds. So even if you don't read or write anything from the host side to a V-Series volume, WAFL does the things it's designed to do. Btw. besides the CP's that also raid scrubbing and other housekeeping stuff that would just not let the lun appear idle to the array.

regards, Niels