Here's a mail from a reader today in reply to a comment I had under an SSD Expresscard report about extending the life/saving space on SSDs by disabling indexing and disabling writing a ram image file on sleep - but I couldn't remember the command to disable hibernate mode. (Also includes a recap of older tips on disabling SMS and LidWake.)
"Subject: Turning off hibernate
Yes, for the current (MLC) generation of SSD, it is recommended to turn off hibernate mode on laptops to preserve drive life (which is a shame, because it would finally make hibernate fast enough to use with 4GB of RAM). I turn it off for my normal HD due to slow sleep when writing a 4GB file, and occasional freezing on wake, which defeats the purpose of safe sleeping anyway. To refresh readers' on the methodology.
Using terminal, enter: sudo pmset hibernatemode 0 (FYI: the -a parameter doesn't seem to be required based on tests w/o it using both battery and AC modes)
Voila. Now simply reboot. (And if you want to reclaim the space the hibernate file takes up (valuable on an SSD), you use terminal for that. The file is found in the /var/vm/ folder, and is named sleepimage. Simply sudo rm that file.)
(FYI - There's also a utility (free) called "smart sleep" mentioned in a later post on More notes on Disabling Hibernate mode)
You can confirm the change with sudo pmset -g which also shows you the other variables in your power management settings. You can change things like lidwake as well, setting it to 0, which will mean you can open the lid, but it won't wake the machine until you press a key. This is a worthwhile change to make, as it will eliminate the occasional failure to wake from sleep problem (solid white light, but black screen). (Disabling lid wake switch was also a tip from years ago where some readers w/notebooks (older models w/lid release buttons) put in carry bags accidently had the lid release tripped during travel - resulting in the battery being drained.-Mike)
This is also where you can turn off sms (sudden motion sensor), which is not necessary for drives with their own sms like certain WD Scorpio drives (and can cause random freezing), and also unnecessary and may cause conflicts with those using SSDs on the SATA bus.
-Mike K."
The terminal command for disabling SMS is sudo pmset -a sms 0. (From an Apple doc on Mac notebooks: About the Sudden Motion Sensor, first posted for late model PB G4s that were the first mac notebooks with SMS.) Disabling SMS was a tip from several years ago here (2006) for some Scorpio drives that would cause a Kernel Panic if SMS was triggered. A reader that was affected by the Scorpio/SMS issue said (in March 2007, on the OS X 10.4.9 reports page) that per an Apple Engineering reply to his bug report, that issue was fixed in OS X 10.4.9, and I have not had anyone mention the Scorpio/SMS issue for years now. (There was some older discussions on Scorpio models with and without the (WD term) "free fall" sensor - many drive db reports (SATA Scorpios) from the past were on BEVS suffix drives - although I remember some notes on Scorpio "black" models that said BJKT suffix had the FFS and BEKT didn't IIRC, but I could be mistaken.)
(BTW - I've never used it personally but a reader suggested using Spotless (shareware) to disable -content indexing- rather than disabling all indexing via Spotlight privacy prefs.
Update/FYI: In fall 2012, another utility was released to enable TRIM, disable sleep image file and more - Chameleon SSD Optimizer. (I've not used it personally.)
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