Howto spin down HD when idle?

finr · Tux's lil' helper Joined: 24 Feb 2004 Posts: 126

Hi all!

My PC is pretty much running all day long, even when I'm not working on it. So I figured my HDs would have a longer life if they were spinned down after eg 30 minutes of inactivity.
The problem is that I don't really know where to start configuring things. I know that hdparm -S should do the job, but I've read a few things in here and most pointed to things like APM and ACPI. ACPI is supported on my machine, and even powering the PC off after shutdown mostly works, but I couldn't figure out how to configure acpid to spin down my HDs, and I even don't know if this is acpid's duty or if hdparm -S should be sufficient...

I'd be grateful if someone could give me a quick explanation as for which tool is the right one to use, and even better, how to use it

BTW: I'm running the gentoo-dev-sources (2.6.3) here...

TIA!
finr

adaptr · Posted: Wed Mar 17, 2004 3:05 pm Post subject:

You can't normally shut down a drive that runs Linux, since the loggers write to it every so often - about once a minute I think.
So not only would you have to configure the HD spindown, but you would have to tweak things so the log files don't get written to more than say once per every few hours.

On a production system this is really not feasible, on a server it is suicide.

Why would you want to do this ?
If the system is truly idle, why not turn it off ?

The average HD doesn't consume much power - in the range of 5-8 Watts max.
And its life may actually be prolonged by not switching it on and off more than you have to.
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finr · Tux's lil' helper Joined: 24 Feb 2004 Posts: 126

primero.gentoo · Guru Joined: 23 Dec 2003 Posts: 402

adaptr · Posted: Wed Mar 17, 2004 7:00 pm Post subject:

If you Google for it you'll get plenty of pointers.
IIRC it does involve some advanced tweaking to make sure the kernel doesn't log critical or incidental stuff - which you can't normally stop (for very good reasons!)
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davidblewett · Posted: Wed Mar 17, 2004 8:54 pm Post subject:

Try using hdparm. You can use it to set a hard drive to power off after a certain period of time. I have it set on my 2nd hard drive, that contains my backups and mp3s. Since it's only accessed intermittently, it made sense for me to do that... I'm not sure of the exact switch, try man hdparm.

SIR · Posted: Wed Mar 17, 2004 9:31 pm Post subject:

Rainmaker · Posted: Wed Mar 17, 2004 9:55 pm Post subject:

Why not just use the BIOS settings?

as long as you've configured you're kernel with APM support, this should work

lightvhawk0 · Guru Joined: 07 Nov 2003 Posts: 388

write a script that checks to see if login is running and if its not it would do a hdparm -y /dev/hdXX. and you could use a cron job to make it run every hour.

This would make it so that every hour it sees if you or root is logged in. if your not it will shut down your hdd
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adaptr · Posted: Thu Mar 18, 2004 8:36 am Post subject:

daemonknight · n00b Joined: 19 Nov 2003 Posts: 16 Location: London

Hi there,

I work at a Data Recovery company, just to note that it is not always the best thing to shutdown your drive the whole time to extend it's life....the most stress that the drive can go through is when you power it up...if you are needing to have a machine on most of the day then I would definatly advise you to keep it spinning.

Thanks
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steima · n00b Joined: 27 Sep 2003 Posts: 18 Location: Austria

OK ... the lifetime of a harddisc would be much higher if it would spin all day and all night.

but fast harddiscs are noisy!

I had the same problem with my little server in my flat. My flat is quite small an especially at night I don't want to hear the hard disc.

So noflushd (eventually in combination with hdparm -S) is the clue. noflushd prevents the flushdeamon to flush every write to disc.
You have to know that systemloggers and so on usually only WRITE to the disc but not read it.

noflushd allows those processes to write to disc but it flushes only if really necessary. If there is a process which reads data from the disc it is spun up and also all unflushed buffers get flushed to disc and of course if the buffer is full the disc is also spun up and everything is flushed to disc.

an emerge noflushd .. installed my noflushd

and you can configure it in /etc/conf.d/noflushd .. as I can remember.

Sometimes noflushd does not spin down the discs ... so you have to set the timeout value for spindown "manualy" with hdparm -S.

I've set the timeoutvalue from hdparm 1 minute higher than from noflushd.
So after 15 mins noflushd prevents funny writting to disc and after 16 mins the harddics is acutally spun down.

As systemlogger I use metalog. It supports buffered writing of the log files anyway so I specified 25 records to be buffered before writing them to disc.

So if I don't use my server a whole day my harddiscs only spin up for doing a backup.
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steima · n00b Joined: 27 Sep 2003 Posts: 18 Location: Austria

DO NOT USE NOFLUSHD WITH JOURNALING FILE SYSTEMS

ext2 would do the job

on the one hand a journaling filesystem is prevented to write journal logs ... this is usually a very very bad thing.
on the other hand your harddisc would spin up an down all the time because there are always some blocks read from disc when updating the journal.

and I've read somewhere .. that with one of the journaling fs noflushd doesnt work at all.

matthias
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mlybarger · Guru Joined: 04 Sep 2002 Posts: 480

so what's the conclusion here on how to spin down a non use hdd? (can't the system itself in general be put to sleep, ie, cache all ram to hdd, and sleep the main system?) how? maybe a guide somewhere... humm....

steima · n00b Joined: 27 Sep 2003 Posts: 18 Location: Austria

as far as i know suspend to ram works quite well with kernel 2.6 systems.

but ... the system is available faster if you just spin down the harddisc. especially for servers it is highly recommended to keep them running ;-)

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mlybarger · Guru Joined: 04 Sep 2002 Posts: 480

do you know where to find a good doc on how to set this up and what is required? i assume if the system is suspended, then things like cron jobs just don't get executed? how about if remote system suddenly tries to access the nfs mount? does system wake up? maybe this is why my NIC's have a wol connector?

really, i'm at work all day long most days and the systems sit here on doing nothing. heck, most nights they do nothing

. it would be nice if they could suspend w/o having to actually boot up. sure it'll take some time to wake up, but w/o the boot process.

steima · n00b Joined: 27 Sep 2003 Posts: 18 Location: Austria

i did never try suspend to ram functionality but im sure that features like wake on lan would work too.

cron jobs could eventually get executet with the mechanism of acpi alarms. as far as i know these alarms are programmed to a timer component of the acpi subsystem. acpi should wake your computer if a alarm occures ... but dont ask me if that really works!
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odegard · Posted: Wed Mar 31, 2004 1:12 pm Post subject:

Use the B flag.

Bob P · Advocate Joined: 20 Oct 2004 Posts: 3374 Location: USA

you can use the "hdparm -Sxxx" parameter to control the elapsed time between drive inactivity and spindown.

Jerem · Apprentice Joined: 11 Jun 2004 Posts: 177

darklegion · Guru Joined: 14 Nov 2004 Posts: 468

Couldn't you just use tmpfs to redirect logging direclty to ram instead of a hdd,thus eliminating the hdd to spin up every few minutes but still keeping possible critical logs visible?

Bojan

vonhelmet · Posted: Tue Feb 01, 2005 11:51 am Post subject:

The greatest stress on the disk will be during large changes in momentum. It's like cars taking a fair whack of petrol to stop and start again. It takes a lot of energy to get things ticking over in the first place. In the case of a hard disk it will take quite a wedge of energy to get it from 0 to 7200 rpm or whatever in a short time, and that puts a strain on the disk.

Leave it running, or turn the PC off if you're looking to save energy.
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Bojan · Posted: Tue Feb 01, 2005 12:29 pm Post subject:

I couldn't agree more. Besides HDD cooling just might be a good idea if you wish to prolong its life.

Sachankara · Posted: Tue Feb 01, 2005 2:51 pm Post subject:

echo 1 > /proc/sys/vm/laptop_mode

Lowers the amount of filesystem journal log-writes so the harddrive has time to spin down...

echo 20 > /proc/sys/vm/swappiness

Forces the kernel to use most of the physical RAM before resorting to using the swap...

Both of these two will reduce the disk access...
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