[Ukfreebsd] "green" HDDs

Bruce Cran bruce at cran.org.uk
Tue Jan 11 15:17:38 GMT 2011

On Tue, 11 Jan 2011 12:08:56 +0000
David Cantrell <david at cantrell.org.uk> wrote:

> A drive that has spun down to save energy but which will come back to
> life on demand should still show up as being available to the OS.  If
> it doesn't, that's a fairly serious bug.

The ata(4) driver does have serious bugs like that unfortunately: I
think it has perhaps been fixed now but for too long the timeout was set
assuming a disk could be accessed within 2 seconds or so - the ATA
specification allows a disk to take 30 seconds. There also at least
used to be panics when reactivating a drive on certain controllers.

Bruce Cran

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