Current-Users archive

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Old Index]

Re: Hot plugging of SATA disks doesn't seem to work under NetBSD-4.x?

On Sep 5,  7:14am, "Sarton O'Brien" wrote:
} On Tue, 15 Apr 2008 09:23:26 am John Nemeth wrote:
} >      In general SCSI disks aren't hot pluggable unless they're hanging
} > off a hot pluggable bus such as Cardbus or PCMCIA (or inside a RAID
} > enclosure where the RAID controllers deals with drives coming and
} > going).
} I just noticed Thor's email as I hit reply ...
} I thought I'd mention that in my experience, most enclosures or hot swap 
} bays/backplanes are just extensions of the controller. I believe there are 
} power filtering components and connectors designed for this specific purpose 
} but there are no additional 'smarts' involved.

     If it's not a proper hot swap bay/backplane then you're likely to
do bad things to the signals during connect/disconnect and can crash
the SCSI bus.  Hot swap connectors are designed so that the grounds
connect first / disconnect last.  This helps prevents the signals and
power from doing bad things.

} >      SATA drives aren't currently hot pluggable.
} I'm not sure of the software requirements, and I loathe to pull a drive from 
} my raid to personally find out if it is possible ... but are you definitely 
} sure? Is it stated somewhere?

     SATA / SAS drives are physically hot swappable.  Since each drive
is connected by a seperate cable there's no need to worry about
disrupting a bus.

     NetBSD's SATA support is wdc with extra smarts to talk to some
SATA controllers in native mode.  To the best of my knowledge there is
no software support for hot swapping.

     If you have a SATA RAID controller which aggregates all the drives
and presents a single logical drive to the host, then it may deal with
hot swapping by itself in a way that is more or less transparent to the

}-- End of excerpt from "Sarton O'Brien"

Home | Main Index | Thread Index | Old Index