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Laptops, power management, and UbuntuLaptops, power management, and UbuntuPosted Nov 8, 2007 9:07 UTC (Thu) by jimparis (subscriber, #38647)Parent article: Laptops, power management, and Ubuntu For "hdparm -B", 255 is reserved by ATAPI spec, so the behavior could be anything. Anything from 128 to 254 should prevent the drive from spinning down. See Table 43 here.
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Laptops, power management, and Ubuntu Posted Nov 11, 2007 16:47 UTC (Sun) by jengelh (subscriber, #33263) [Link] It would be a wonderful world if this was the case. The Toshiba MK2003GAH is one of these drives that do parking anyway, even if you -B255 it. Only solution was to write a kernel-level workaround module (I called it thkd) that periodically reads small amounts from the disk.
Laptops, power management, and Ubuntu Posted Nov 11, 2007 17:29 UTC (Sun) by jimparis (subscriber, #38647) [Link] -B255 is reserved, it's no surprise that it still parks the heads.
Laptops, power management, and Ubuntu Posted Nov 11, 2007 17:31 UTC (Sun) by jimparis (subscriber, #38647) [Link] Wait, maybe you meant it also parks with -B128 through -B254, in which case I agree, yes, that sucks. I'm not sure why you need a kernel module though, seems a small user-space utility that does periodic reads with O_DIRECT would work just as well.
Laptops, power management, and Ubuntu Posted Nov 11, 2007 17:39 UTC (Sun) by jengelh (subscriber, #33263) [Link] Because the kernel module is smaller (11KB - what, who bloated that up?), does not need glibc, or anything and runs as early as possible without having to mess with the distribution-specific boot scripts. Rebuilding the initrd _with_ your changes is often a real pita.
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