Mailinglist Archive: opensuse (1606 mails)

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Re: [opensuse] Opensuse doesn't wait long enough for the disks to spin up before trrying to configure raid

----- Original Message -----
From: "Mike Myers" <mikesm559@xxxxxxxxx>
To: <opensuse@xxxxxxxxxxxx>
Sent: Saturday, August 30, 2008 3:31 PM
Subject: Re: [opensuse] Opensuse doesn't wait long enough for the disks to spin
up before trrying to configure raid

I don't think that's going to fix it. The way the libata
driver works is that it spins the disks up one at a time
(staggered spinup). Just powering the system on will not
cause the disks to spin up. After the start of the boot,
/ is mounted and the sata driver begins doing all of it's
work, finding the PMP's on the SATA ports, and then probing
each PMP, id'ing the disks and spinning them up, etc...
So this is all happening way after the boot is started.

Every piece of hardware I ever saw spun the disks up on it's own, and that
includes lots of scsi and sata and sas raid arrays, including the use of sata
port expanders/multiplexers. Usually the bios involved (maybe a raid card,
maybe a motherboard) offers an option to stagger the spinup, configureable
seconds between disks, or configurable seconds between sets of N(configurable)
disks at once, configurable seconds to wait in total, or all of the above.

Then libata will find every disk ready to go on the first try and that whole
sequence should shoot through fast and not screw up md mounting.

However I do think the way you are trying to fix it is the more correct fix.
The assmbly and mount stages should obviously block until the spinup stage is
done, and the spinup stage should obviously have a timeout per disk and no
fixed total timeout.

However-However... Even IF the raid card and mb offer no way to avoid starting
all disks at once, a box like that should probably have a dual or triple
redundant, hot-swap power supply anyways. (you bought 18 hot swap disks but
only a plain jane single not-hot-swap ps?) It might be too much for one power
supply to spin up all at once, but as long as you have both plugged in and both
work, then no problem. You're only vulnerable when one ps dies until you get
it's replacement in. And since they're hot swap, you can have the spare sitting
there on hand already and pop it in immediately.

Brian K. White brian@xxxxxxxxx
filePro BBx Linux SCO FreeBSD #callahans Satriani Filk!

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