ZFS RAIDZ and atacontrol spindown settings

[Ivan Voras]

Mark Stapper wrote:
> Good day,
> 
> I am the proud user of a FreeBSD 7.2 AMD64 system housing, amongst other
> things, a data server.
> My "server"(It's called "Yoshi") runs FreeBSD from a mirrored system
> disc, and has a zfs RAIDZ array with 4 discs for bulky data.
> As it is a home server, and I work during the day, these four discs were
> spinning happily all day long without much use for them doing so.
> To save the world(and money) I issued the command "atacontrol spindown
> 1800" for all the discs in my array spinning them down after thirty
> minutes of idle spinning.
> So far so good, me very happy! However, when I access the array after
> the discs have been spun down, it spins up the discs one after the other...
> Mind you one AFTER the other, taking 4*9 seconds to do a "ls" command on
> my music directory.
> Content as I am with the smooth down- and upspinning of the disks, I
> would like it better if the four discs would spin up simultaneously.
> Thus my  question: "Is it possible to \"group\" discs to be spun up
> together, or to issue a custom command upon upspinning of a disc such as
> to spin up other disks?"

Good question but the answer is probably no - it really only depends on 
how ZFS accesses the drives; if it accesses them in sequence, you can't 
change it.