Re: Resizing a zpool as a VMware ESXi guest ...

On 0510T1522, Matthew Grooms wrote:
> On 11/28/2015 10:03 PM, Matthew Grooms wrote:
> > On 11/28/2015 6:10 PM, Matthew Grooms wrote:
> >> On 11/27/2015 7:44 PM, Matthew Grooms wrote:
> >>> I spent the day looking over the FreeBSD cam and scsi_da source code.
> >>> After sprinkling a bunch of printf's around to see what code paths
> >>> were being called, It's obvious that Edward was correct in assuming
> >>> that ESXi doesn't return any 'Unit Attention' sense information in
> >>> response to a 'Read Capacity' request. This kinda makes sense as ESXi
> >>> emulates SCSI-2 disk devices and, as far as I can tell, the 0x2A/0x09
> >>> ASC/ASCQ sense code that denotes 'Capacity Data Has Changed' wasn't
> >>> defined until the SCSCI-3 spec. It's frustrating that the only way to
> >>> get the scsci_da code to call reprobe() is by receiving a command
> >>> from the device. Would something like this work? ...
> >>>
> >>> 1) Register a callback using xpt_register_async( daasync,
> >>> AC_REPROBE_DEVICE, path ) that calls reprobe()
> >>> 2) Implement a new IOCTL in cam_xpt that camcontrol can call with the
> >>> bus:target:lun as the argument
> >>> 3) have cam_xpt capture the IOCTL request and call xpt_async(
> >>> AC_REPROBE_DEVICE, path ) as a result
> >>>
> >>> This way users would have the option of manually asking cam to
> >>> communicate the new size to geom. The only option now is one or more
> >>> reboots to gain access to the increased disk capacity. If this sounds
> >>> like a reasonable approach, I'll take a stab at implementing it.
> >>>
> >>
> >> Here is a proof of concept patch. I'm a complete noob when it comes to
> >> cam, scsi or freebsd kernel development for that matter, so I'm sure
> >> it could have been done a better way. In any case, I added a new
> >> command to camcontrol that allows you to specify a bus, target and lun
> >> as an argument. For example ...
> >>
> >> # camcontrol readcap da1 -h
> >> Device Size: 32 G, Block Length: 512 bytes
> >>
> >> # gpart show da1
> >> =>      40  58720176  da1  GPT  (28G)
> >>         40  58720176    1  freebsd-ufs  (28G)
> >>
> >> Note, I resized the VMDK disk in ESXi. The camcontrol output shows the
> >> size as 32G but geom thinks its 28G.
> >>
> >> # camcontrol devlist
> >> <NECVMWar VMware IDE CDR10 1.00>   at scbus1 target 0 lun 0 (cd0,pass0)
> >> <VMware Virtual disk 1.0>          at scbus2 target 0 lun 0 (pass1,da0)
> >> <VMware Virtual disk 1.0>          at scbus2 target 1 lun 0 (pass2,da1)
> >> <FREEBSD CTLDISK 0001>             at scbus3 target 0 lun 0 (da2,pass3)
> >>
> >> # camcontrol reprobe 2:1:0
> >>
> >> This generates an event that is captured by the scsci da device to
> >> forces a reprobe. The kernel output looks almost identical to when the
> >> 'Unit Attention' sense data is received ...
> >>
> >> Nov 28 17:46:13 iscsi-i kernel: (da1:mpt0:0:1:0): Re-probe requested
> >> Nov 28 17:46:13 iscsi-i kernel: GEOM_PART: da1 was automatically resized.
> >> Nov 28 17:46:13 iscsi-i kernel: Use `gpart commit da1` to save changes
> >> or `gpart undo da1` to revert them.
> >>
> >> Now that geom knows about the increased disk capacity, I can increase
> >> the partition size and grow the fs ...
> >>
> >> [root_at_iscsi-i /home/mgrooms]# gpart show da1
> >> =>      40  67108784  da1  GPT  (32G)
> >>         40  58720176    1  freebsd-ufs  (28G)
> >>   58720216   8388608       - free -  (4.0G)
> >>
> >> # gpart resize -i 1 da1
> >> da1p1 resized
> >>
> >> # growfs da1p1
> >> Device is mounted read-write; resizing will result in temporary write
> >> suspension for /var/data1.
> >> It's strongly recommended to make a backup before growing the file
> >> system.
> >> OK to grow filesystem on /dev/da1p1, mounted on /var/data1, from 28GB
> >> to 32GB? [Yes/No] Yes
> >> super-block backups (for fsck_ffs -b #) at:
> >>  58983232, 60265472, 61547712, 62829952, 64112192, 65394432, 66676672
> >>
> >> # df -h
> >> Filesystem    Size    Used   Avail Capacity  Mounted on
> >> /dev/da0p3     18G    5.3G     12G    31%    /
> >> devfs         1.0K    1.0K      0B   100%    /dev
> >> /dev/da1p1     31G     32M     28G     0%    /var/data1
> >> /dev/da2p1     15G     32M     14G     0%    /var/data2
> >>
> >> Sure would be nice to have something like this in the tree. It's
> >> really a drag to have to reboot production VMs to increase disk
> >> capacity when it could be easily avoided. I'm not sure what the
> >> correct IOCTL should look like. Maybe CAMIOCOMMAND is a better way to
> >> go? If someone with some experience with the cam/scsi subsystems was
> >> willing to give me some direction I'd be willing to try and rewrite
> >> the patch in a way that would be commit worthy. I just need some
> >> direction.
> >>
> >
> > Ok, last post until I get some feedback. Here's a new version of the
> > patch complete with man page updates. It communicates via CAMIOCOMMAND
> > instead of introducing a new ioctl value. I tried to model it after the
> > device reset option, hopefully with some degree of success. Functionally
> > it should be the same as the first patch.
> >
> 
> The PR 204901 filed for this can be closed now that the author (ahem) 
> has committed support for the camcontrol reprobe command ...
> 
> https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=204901
> https://docs.freebsd.org/cgi/getmsg.cgi?fetch=866020+0+current/svn-src-head

Ugh.  I honestly have no idea how did I manage to miss your patch.
I did remember the discussion, I remember asking mav_at_ about what's the
best way to hook it up to CAM, but until yesterday I just didn't know
the patch (and the PR) existed.  Sorry for that.  Guess that's what
happens when I try to keep up with too many unrelated subprojects
at the same time.