Tugger the SLUGger!SLUG Mailing List Archives

Re: [SLUG] hot swapping hard drives


On Sat, May 16, 2009 at 6:19 PM, Daniel Pittman <daniel@xxxxxxxxxxxx> wrote:

> Tony Sceats <tony.sceats@xxxxxxxxx> writes:
> >>> The CLI command "umount" does this within the Linux / Unix OS.
> >>
> >> That should have the filesystem flush data, but doesn't actually push
> >> out dirty pages for the device — if you accessed it raw at any point
> >> this will not be sufficient.
> >>
> >> (Also, lower layers such as LVM, software RAID, etc, might not flush
> >>  their data during the unmount process.)
> >>
> >>> The "sync" command/programming API call is another way to do this
> >>> programmatically.
> >>
> >> That will flush raw blocks from the device also.
> >>
> >>> That is all that is required.
> >>
> >> Those are necessary, but not sufficient, steps, I fear.
> >
> > so if our raw partitions are up-to-date and the file systems are also,
> > thanks to the 'sync' and 'umount' commands done before device removal,
> > what else are you implying would be necessary before the drive is
> > safely pulled?
>
> Didn't I already answer this in the text you cut?
>
> Your controller needs to support SATA hotplug sanely.  Your controller
> needs to report the event to the driver.  The driver needs to handle the
> event sanely.




o sorry :(  I had taken all that on board and I had just read it as though
you were alluding to more things being necessary even again, that's all.. in
fact it's precisely because I thought you'd had it all pretty well covered
that I was confused by that line..


anyway, classically wrong reading of language in an email, who would ever
have thought ;)