[mythtv-users] raid array spin down possible?

[digid myth]

I have the drives in my raid 1 set to sleep with -S120 do not set the time
to low, starting and stoping the drives can be hard on them if you set the
time too short. My previous setup was with raid 5 and worked well also. It
took a while to get them to stay sleeping as there are lots of things in
linux that want to wake them up. The two biggest things are the access time
stamps on files and folders. Be sure you mount them with noatime,nodiratime,
in your /etc/fstab file. The other thing that will keep waking them up is
the SMART monitoring utilities. Be sure to set the -n standby in your
/etc/smartd.conf file. This will keep smartd from scanning the drives if
they are sleeping. If your drives are getting too hot when they are running
then you need to find some way to cool them down!!!!!!! Heat will destroy
the drives. All my drives have fans blowing directly across them. If you
value your data you need to keep those drives cool at all times. Most cases
do not do a good job of keeping drives cool. I recently upgraded my case to
a Diablotech EVO Mid which I am very happy with for a $40.00 budget case. I
also added a cool master 4 in 3 drive mount
http://www.newegg.com/Product/Product.aspx?Item=N82E16817993002 which
allowed me to add 4 additional drives with a fan cleanly. I can not stress
enough the need to keep the drives cool. Spinning them down should only be
needed to save on power!!!

Dale


On Mon, Sep 26, 2011 at 1:31 PM, Neil Cooper <neilcoo at yahoo.co.uk> wrote:

> Hi,
>
> My backend has a single 1TB HDD (for booting/OS and recorded TV shows) and
> also 3 HDDs in a raid array for saved shows, other media and general NAS.
> The array is a Linux "software" type (i.e. mdadm --create) raid 5. All
> drives are SATA. It's running "standard" Ubuntu 64 11.04 (not mythbuntu).
>
> Both because the raid array is hardly ever in use and because the box gets
> very hot with all drives running, I would like to spin down (just) the raid
> array whenever possible.
>
> I've tried from the command line:
> sudo hdparm -S 1 /dev/sdb /dev/sdc /dev/sdd
> I also have uncommented/modified the spindown setting to 1 in hdparm.conf
> but still the drives don't ever actually spin down. Even though nothing I'm
> doing is accessing the raid array.
>
> The 1 value equals a spindown in 5 seconds of no-use. I'm reasonably (but
> not 100%) certain that the OS isn't accessing the array, at least not as
> often as every 5 seconds.
>
> I read an earlier thread here that SATA drives might not respond to hdparm
> -S and that in those cases sg3-utils and/or spindown might work, however a
> later post disputed that. Also those seem to do the equivalent of ejecting
> the drive. I'm afraid to try them as I'm not even sure it would be safe with
> drives already in a raid array.
>
> Any advice on how can I get my raid array to spin down?
>
> Also, is there any way from the command line to see if a drive is actually
> in a spun down state or not?
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