DevSlp

{{short description|Low-power feature in some SATA devices}}

DevSlp or DevSleep (sometimes referred to as device sleep or SATA DEVSLP) is a feature in some SATA devices which allows them to go into a low power "device sleep" mode when sent the appropriate signal, which uses one or two orders of magnitude less power than a traditional idle (about 5 mW,{{cite web|url=http://www.tomshardware.com/news/BIWIN-mSATA-SSD-Efficient-M5301,22839.html|title=Tom's Hardware review of BIWIN announcement of using DevSlp|author=Niels Broekhuijsen|work=Tom's Hardware|date=2 June 2013 }} but some drives can get as low as 2.5 mW{{cite web|url=http://www.tomshardware.com/reviews/transcend-ssd340-jmicron-jmf667h-performance,3820-10.html|title=Tom's Hardware review of the Transcend SSD340|author=Christopher Ryan|work=Tom's Hardware|date=28 July 2014 }}). The feature was introduced by SanDisk{{cite web|url=http://www.tomshardware.com/news/SATA-DEVSLP-Initiative-50mW-low-power,13419.html|title=Toms Hardware DevSlp initiative|author=Kevin Parrish|work=Tom's Hardware|date=13 September 2011 }} in a partnership with Intel.{{cite web|url=http://www.storagereview.com/intel_and_sandisk_join_forces_for_new_sata_devslp_standard_idf_2011|title=StorageReview coverage of DevSlp standard|publisher=|access-date=2014-08-20|archive-date=2016-03-04|archive-url=https://web.archive.org/web/20160304001913/http://www.storagereview.com/intel_and_sandisk_join_forces_for_new_sata_devslp_standard_idf_2011|url-status=dead}} Some think that the initiative could make laptops feel like they power on basically instantaneously,{{cite web|url=http://www.techspot.com/news/53246-sata-devsleep-getting-us-closer-to-instant-on-laptops.html|title=Techspot review of feature|work=TechSpot|date=16 July 2013 }} while others state that this means that laptops can stay on all the time, and always be available with no adverse effects on battery life.{{cite web

| url = http://www.maximumpc.com/article/news/new_power-saving_devsleep_feature_added_sata_specification

| title = New Power-Saving DevSleep Feature Added To SATA Specification

| date = 6 January 2012 | accessdate = 8 July 2015

| author = Brad Chacos | website = maximumpc.com

}}

In traditional low-power modes, SATA link still needs to remain powered on to allow the device to receive a wake-up command. With DevSlp, rarely used 3.3 V pins of the SATA power plug will be used for the DevSlp signal instead of providing 3.3 V power. This signal can wake up the drive, and it will allow SATA link to be shut down, reducing further the power consumption.{{cite web|url=http://www.heise.de/ct/hotline/SSD-mit-Devsleep-Funktion-2238150.html|title=c′t Hotline SSD mit "Devsleep"-Funktion (German article)|date=25 June 2014|work=c't|access-date=16 November 2014|archive-date=28 October 2021|archive-url=https://web.archive.org/web/20211028085802/https://www.heise.de/ct/hotline/SSD-mit-Devsleep-Funktion-2238150.html|url-status=dead}}

Due to the way they work, DevSleep-enabled drives may not be suitable for most desktop PCs and some notebooks with the 3.3 V voltage present in their SATA power connectors; the presence of 3.3 V results in DevSleep-enabled drives remaining in DevSlp state. An incompatibility between a desktop mainboard and a SATA SSD may be resolved by disabling the DevSleep feature using a power connector adapter that does not pass the +3.3 V line.{{Citation needed|date=August 2015}}