SSD Spin down


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1 hour ago, exist2resist said:

I understand that they don't spin down, but my understanding is instead SSDs are able to go into low power mode.

Quite possibly, but the point here is that the normal positives and negatives of spinning a disk down or keeping it spun up don't apply to SSD's. For spinning drives, when they are spun down, they take an eternity in computer time to get running again. Not so for SSD's. Keeping an SSD in "full power" mode isn't going to make any real difference to a network client, or even a local one for that matter. Similarly, the amount of power difference between an idle SSD and one in "low power" mode is very insignificant. The amount of power needed to WRITE to an SSD is much greater of a percentage difference. Even if you had a full server with only SSD's, the difference would be tiny between idle and "low power".

 

Also, because there isn't much of a benefit, some models of SSD don't even support power levels like hard drives do, they may accept the commands but not really do anything. Perhaps @johnnie.black has done some testing on his all SSD test server, I don't remember if he posted on it or not.

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1 minute ago, jonathanm said:

Perhaps @johnnie.black has done some testing on his all SSD test server, I don't remember if he posted on it or not.

 

Not really, idle SSDs usually use so little power that I never really worried about that, doubt that it would be a measurable difference with 2 or 3 SSDs, also don't see the point in having them not "spinning down" since like Jonathanm mentioned they wake up instantly, but if the OP really wants that he just needs to click on each SSD and set spindown to never.

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On 8/11/2017 at 5:33 PM, johnnie.black said:

 

Not really, idle SSDs usually use so little power that I never really worried about that, doubt that it would be a measurable difference with 2 or 3 SSDs, also don't see the point in having them not "spinning down" since like Jonathanm mentioned they wake up instantly, but if the OP really wants that he just needs to click on each SSD and set spindown to never.

 

On 8/11/2017 at 5:26 PM, jonathanm said:

Quite possibly, but the point here is that the normal positives and negatives of spinning a disk down or keeping it spun up don't apply to SSD's. For spinning drives, when they are spun down, they take an eternity in computer time to get running again. Not so for SSD's. Keeping an SSD in "full power" mode isn't going to make any real difference to a network client, or even a local one for that matter. Similarly, the amount of power difference between an idle SSD and one in "low power" mode is very insignificant. The amount of power needed to WRITE to an SSD is much greater of a percentage difference. Even if you had a full server with only SSD's, the difference would be tiny between idle and "low power".

 

Also, because there isn't much of a benefit, some models of SSD don't even support power levels like hard drives do, they may accept the commands but not really do anything. Perhaps @johnnie.black has done some testing on his all SSD test server, I don't remember if he posted on it or not.

I notice the VM tab hanging a bit when the SSD is in low power/standby mode.

So I want to set the SSD to never go into that state. 

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There is a way to set spindown on non-array disks as well. Just not via the GUI. Forgot the command but can look it up if you are interested.

 

I thought this was ignored for SSDs. An SSD doesn't do too much spinning, unless you tie a string to it and whirl it through the air over your head. :D

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On 8/14/2017 at 0:19 PM, bjp999 said:

There is a way to set spindown on non-array disks as well. Just not via the GUI. Forgot the command but can look it up if you are interested.

 

I thought this was ignored for SSDs. An SSD doesn't do too much spinning, unless you tie a string to it and whirl it through the air over your head. :D

 

Looks like it can be accomplished using hdparm command

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4 minutes ago, exist2resist said:

 

Looks like it can be accomplished using hdparm command

Yep, that's it. There are some weirdities about having to power down to reset some of the hdparm settings.as I recall, but spindown time may not be a problem. Set then in your go file or via a script that runs once per bout.

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