Hot-Swapping hard drives on Dell PowerEdge 2850 running FBSD 5.5-PRE

Alex Franks arfranks at
Fri Jun 23 18:13:48 UTC 2006

On 6/23/06, Alex Zbyslaw <xfb52 at> wrote:
> Alex Franks wrote:
> > Hello all,
> >
> > I'm getting ready to install 2 identical drives into the available
> > drive bays in my 2850. However, it would be highly preferable that
> > this machine NOT be shut down in order to install these drives. I know
> > from looking at the docs that these drive bays are hot-swappable, but
> > I'd like to know before I attempt this that someone else out there has
> > successfully performed a hot-swap or hot-install of drives on a 2850
> > or comparable Dell PowerEdge running FreeBSD.
> RAID-1 I assume and PERC 4e/Di.  Yes, did it when testing fresh
> machines.  The controller BIOS has a setting for how much resource to
> allocate to the recovery of the inserted drive (0?-100%); the lower you
> set it the slower it will recover the disk, but the higher you set it
> the slower the machine will go. I think we went for 70% as the machine
> never gets *that* heavy disk usage.
> If the machine isn't live yet, then just do a basic install from CD (<30
> mins) and then try the hotswap test.  That way you can't lose any data
> even if something goes wrong.
> My advice with these machines is never to swap any disk with the machine
> off - the controller gets confused.  Stick with hotswapping and it seems
> fine.  I think you can set up an auto-spare so that if a disk fails the
> array is rebuilt automatically using the spare.
> Use sysutils/megarc for monitoring the RAID from BSD.
> --Alex

Thanks for the input,

The drives hot-plugged just fine. The machine was live when I plugged
the disks and still is right now. I'm trying to avoid another trip to
the colo today to (safely) reboot by finding out if/where the drives
are loaded at the hardware level and how I can go about mounting them
to logical partitions. At this point, I'm not as concerned about
getting the 2 drives into RAID1 since they're going to be used for
backup purposes and will not be used in a high volume capacity (for
now), and since this would almost certainly require a reboot. I *know*
rebooting is preferable, but I'm experimenting here, and uptime is
pretty important since the server is the main mysql box for a handful
of websites.

The controller is a Perc 4e/Di as assumed, and I'm still a little
unsure as to whether the 2 drives that shipped with the machine are
currently set up in a RAID array. The current filesystem is mounted on
/dev/amrd0s1[a-f] and I would expect to find the new drives named
similarly after using some useful utility that I'm unaware of. Any

Thanks again.

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