On Fri, 07 Apr 2000, Sven Kirmess wrote:
> Thursday, April 06, 2000, 10:08:59 PM, Jakob wrote:
>
> Sorry, but I have to say it. Very, very good HOWTO. Thanks.
*Blush* :)
> >> Why not? I think about power down after e.g. 30' idle time. Not
> >> after a few seconds... What's the Problem with RAID? Does it mark
> >> all disks as bad if they don't come up fast enough?
> > It definitely shouldn't. That would be a bug in the drive if you got
> > a read/write failure after power down.
>
> But Linux may have a timeout...?
You're right. It has none that I know of. I would be surprised if
there was a timeout (I'm really sure there isn't), as this would be
some experimental value that you could never really give a ``right''
value.
>
> > On a home system where the disks can potentially be idle for a long
> > time, you could probably spin the disks down. On a production system
> > where users expect a prompt reply from the system, powering down the
> > disks is outright stupid.
>
> Of course it isn't a productive system.
>
> > But I fail to see how this relates to the size of the PSU ? All
> > disks must run when you use them, and if you need a 300W PSU to do
> > that, you can't use a 150W even if your disks are only in use 50% of
> > the day. (Obviously)
>
> I know that of course. My question was more like "Is there a power
> problem with a couple of IDE disks?" or "are you running special
> supplys?".
We have six 6G old Quantum SCSI disks in a home-made RAID tower here.
The disks spin up all at the same time (they're to stupid/old to do
anything else), and they run of a cheap AT PSU. No problems, but
I have no idea what the load is on the PSU when they spin up.
>
> I won't create a RAID system and loose more data because of a too weak
> supply than I would loose during a disk failure.
I think that if you get past a synchronous spinup, you'll survive
anything that might happen during use. But this is all a ``may''
and ``might'' discussion...
>
> > By the way, a lot of modern IDE drives have a jumper setting that
> > will delay their spin-up, so you could have your drives spinning up
> > only a few at a time to reduce the peak load, even with cheap disks.
> > At least some IBM disks has this feature (unsure about others)
>
> But this will slow down the wake process even more and maybe lead to
> more misinterpretation of the disk status...?
It will slow the wakeup process if the disks also delay wakeups
after the initial power-on. I don't know what the disks would do,
it probably even depends on vendors too, just to make this whole
thing even more interesting :)
--
................................................................
: [EMAIL PROTECTED] : And I see the elder races, :
:.........................: putrid forms of man :
: Jakob Østergaard : See him rise and claim the earth, :
: OZ9ABN : his downfall is at hand. :
:.........................:............{Konkhra}...............:
