Re: Running cool and silent
On Tue, May 12, 2015, at 08:44, Dan Ritter wrote:
> On Tue, May 12, 2015 at 02:35:45AM -0700, Rusi Mody wrote:
> > # echo "min_power" | tee /sys/class/scsi_host/host*/link_power_management_policy
> >
> > So is this command safe?
It varies. We do not enable it by default because it is known to cause
data loss on some devices: several SSDs are known to corrupt their
contents in "min_power" mode, and there are reports of it causing
oddities on other devices as well, from HDDs to ODDs (for example, some
CD/DVD/BD writers will never complete a sucessful burn in min_power
mode).
Some computer chipsets also have errata that cause misbehavior if
min_power is used, regardless of whether the devices (SSDs, HDDs, ODDs)
support it properly or not.
Therefore, whether it will be safe or not depends not only on your
laptop motherboard, but also on exactly which disks/ssds are installed.
Even when it works perfectly, it sometimes causes unacceptable slow
downs.
You will have to test it for yourself to know whether it will work
properly for you, but beware the risk of data loss and device
misbehavior.
> > Does someone know what it does? [Dont remember where I found it]
It enables the highest level of (in this case, SATA) link power
management.
> This command turns on power conservation for your disks. It's
Actually, it is for the connection between the HDD/SSD/ODD and the
chipset.
The HDDs/SSDs have their own set of commands that enable power
management internal to the disk/SSD itself. Refer to "hdparm -B" for
SATA devices.
--
"One disk to rule them all, One disk to find them. One disk to bring
them all and in the darkness grind them. In the Land of Redmond
where the shadows lie." -- The Silicon Valley Tarot
Henrique de Moraes Holschuh <hmh@debian.org>
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