[dm-devel] multipath-tools libmultipath/configure.c libmu ...

[Pasi Kärkkäinen]

On Tue, Sep 30, 2008 at 02:20:47PM -0500, Benjamin Marzinski wrote:
> On Tue, Sep 30, 2008 at 12:38:43PM +0300, Pasi Kärkkäinen wrote:
> > On Tue, Sep 30, 2008 at 12:22:06PM +0300, Pasi Kärkkäinen wrote:
> > > On Tue, Sep 23, 2008 at 01:05:04PM -0500, Benjamin Marzinski wrote:
> > > > > 
> > > > > Responding to my own mail, I did got the source with the patches from the
> > > > > cvs.  But, the resizing does not work for with with mounted volumes.  There
> > > > > are 4 paths for the volume, so there is no probably with it failing paths. 
> > > > > I get "domap(0) failure for create/reload map" when I run multipath -v 3.
> > > > > 
> > > > > I can get dm to reconize the new size if the volume is umounted.  But, I
> > > > > really would like it to work while it is mounted.
> > > > > 
> > > > 
> > > > It should work for mounted volumes.  Did you try
> > > > multipathd -k"resize map <mapname>"
> > > > 
> > > > Since this requires suspending without the no_flush option, I didn't
> > > > want to have it happen on a normal reload, and since without the kernel
> > > > fixes, this required removing and then readding paths, I did it through
> > > > multipathd.
> > > > 
> > > > So just running multipath -v3 after a path resize won't work. In fact, I
> > > > think it might leave the devices in the suspended state, since the
> > > > resume fails.
> > > > 
> > > 
> > > Hi!
> > > 
> > > I just tried this but I'm having problems getting it to work..
> > > 
> > > # multipathd -k"resize map mpath-resize-test"
> > > fail
> > > 
> > > The underlying SCSI devices have been online resized already, and verified
> > > from dmesg and from /proc/partitions to be bigger.
> > > 
> > > I'm running rhel5 kernel with scsi online resize patches (2.6.18-93.el5.bz444964.2)
> > > and dm-multipath testing packages with support for online resizing
> > > (device-mapper-multipath-0.4.7-19.el5.i386.rpm).
> > > 
> > > Any ideas? 
> > > 
> > 
> > Actually I think the problem was that I had not yet reloaded multipathd
> > configuration, so my underlying devices were still blacklisted according to
> > multipathd -k"show devices".. but still I had the mpath-device up and
> > running :) Oh well..
> > 
> > I ran "/etc/init.d/multipathd reload" and then:
> > 
> > # multipathd -k"resize map mpath-resize-test"
> > ok
> > 
> > But "multipath -ll" still shows the mpath-resize-test device with the
> > same/old size.. 
> > 
> > What to do/try next? 
> 
> Does
> 
> # blockdev --getsize <scsi_device>
> 
> show the new size, after you have increased the scsi device size?
> 

Yep, it does.

> Also, can you start up multipathd with the -v3 option, and copy any
> messages that are printed out when you run 
> 
> # multipathd -k"resize map mpath-resize-test"
> 
> Thanks.
> 

I don't know what went wrong, but my mpath device went into SUSPENDED mode,
and now also multipathd command just hangs.. actually I can't even reboot
the server, 'reboot' command also hangs. "dmsetup resume" doesn't help..

I guess rebooting doesn't work because I have some IO waiting for execution
for that suspended device/filesystem..

I power cycled the server, and tried again.. 

This time it worked OK! 

Differences between my first try (which didn't work) and the 
second (successful) try:

- First time I didn't have multipathd restarted/reloaded to pick up the  
  complete configuration for the LUNs/devices used in this test.

- First time I didn't understand to do 'del/add path' trick.. I went for
  'resize map' immediately. 

"Log" of my successful resize experience is here:
http://pasik.reaktio.net/rhel5-online-iscsi-resize-test.txt

Thanks a lot for your help!

-- Pasi