Messages in this thread | | | Date | Tue, 1 Jun 2004 16:42:24 +0100 | From | John Bradford <> | Subject | Re: Question about IDE disk shutdown |
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Hi,
> Probably a trivial question for ones who know it - what IDE commands does > kernel issue when shutting down (which results in automatic power-off if ACPI > is enabled)? > > According to my hard disk manual, it is absolutely recommended to put the > drive in STANDBY or SLEEP mode before power cut-off because in that way heads > are nicely parked. In that way it is guaranteed to have 300000 head > load/unload cycles minimum, while in other case it is just 20000 cycles. > > It also explicitely states that FLUSH CACHE is not to be used for drive > power-off because it does not park the heads. > > Looking at the source I see in ide-disk.c: > > .gen_driver = { > .shutdown = ide_device_shutdown, > }, > > Following that I see that ide_device_shutdown flushes the cache, and then > calls dev->bus->suspend(dev, PM_SUSPEND_STANDBY); which is in fact > generic_ide_suspend, right? There, something called REQ_PM_SUSPEND is issued > to the drive. As SUSPEND != STANDBY or SLEEP, I am left uncertain. > > Is there a place to be worried or I am missing something?
This kind of thing has been discussed extensively in the past. Basically, there are loads of broken drives which do a wide range of different things, so following the standards doesn't necessarily work best in practice.
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