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a80192b6a7
lvm2/lib
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Jonathan Earl Brassow a80192b6a7 Allow 'nosync' extension of mirrors. 
This patch allows a mirror to be extended without an initial resync of the
extended portion.  It compliments the existing '--nosync' option to lvcreate.
This action can be done implicitly if the mirror was created with the '--nosync'
option, or explicitly if the '--nosync' option is used when extending the device.

Here are the operational criteria:
1) A mirror created with '--nosync' should extend with 'nosync' implicitly
[EXAMPLE]# lvs vg; lvextend -L +5G vg/lv ; lvs vg
  LV   VG   Attr     LSize Pool Origin Snap%  Move Log     Copy%  Convert
  lv   vg   Mwi-a-m- 5.00g                         lv_mlog 100.00
  Extending 2 mirror images.
  Extending logical volume lv to 10.00 GiB
  Logical volume lv successfully resized
  LV   VG   Attr     LSize  Pool Origin Snap%  Move Log     Copy%  Convert
  lv   vg   Mwi-a-m- 10.00g                         lv_mlog 100.00

2) The 'M' attribute ('M' signifies a mirror created with '--nosync', while 'm'
signifies a mirror created w/o '--nosync') must be preserved when extending a
mirror created with '--nosync'.  See #1 for example of 'M' attribute.

3) A mirror created without '--nosync' should extend with 'nosync' only when
'--nosync' is explicitly used when extending.
[EXAMPLE]# lvs vg; lvextend -L +5G vg/lv; lvs vg
  LV   VG   Attr     LSize  Pool Origin Snap%  Move Log     Copy%  Convert
  lv   vg   mwi-a-m- 20.00m                         lv_mlog 100.00
  Extending 2 mirror images.
  Extending logical volume lv to 5.02 GiB
  Logical volume lv successfully resized
  LV   VG   Attr     LSize Pool Origin Snap%  Move Log     Copy%  Convert
  lv   vg   mwi-a-m- 5.02g                         lv_mlog   0.39
vs.
[EXAMPLE]# lvs vg; lvextend -L +5G vg/lv --nosync; lvs vg
  LV   VG   Attr     LSize  Pool Origin Snap%  Move Log     Copy%  Convert
  lv   vg   mwi-a-m- 20.00m                         lv_mlog 100.00
  Extending 2 mirror images.
  Extending logical volume lv to 5.02 GiB
  Logical volume lv successfully resized
  LV   VG   Attr     LSize Pool Origin Snap%  Move Log     Copy%  Convert
  lv   vg   Mwi-a-m- 5.02g                         lv_mlog 100.00

4) The 'm' attribute must change to 'M' when extending a mirror created without
'--nosync' is extended with the '--nosync' option.  (See #3 examples above.)

5) An inactive mirror's sync percent cannot be determined definitively, so it
must not be allowed to skip resync.  Instead, the extend should ask the user if
they want to extend while performing a resync.
[EXAMPLE]# lvchange -an vg/lv
[EXAMPLE]# lvextend -L +5G vg/lv
  Extending 2 mirror images.
  Extending logical volume lv to 10.00 GiB
  vg/lv is not active.  Unable to get sync percent.
Do full resync of extended portion of vg/lv?  [y/n]: y
  Logical volume lv successfully resized

6) A mirror that is performing recovery (as opposed to an initial sync) - like
after a failure - is not allowed to extend with either an implicit or
explicit nosync option.  [You can simulate this with a 'corelog' mirror because
when it is reactivated, it must be recovered every time.]
[EXAMPLE]# lvcreate -m1 -L 5G -n lv vg --nosync --corelog
  WARNING: New mirror won't be synchronised. Don't read what you didn't write!
  Logical volume "lv" created
[EXAMPLE]# lvs vg
  LV   VG   Attr     LSize Pool Origin Snap%  Move Log Copy%  Convert
  lv   vg   Mwi-a-m- 5.00g                             100.00
[EXAMPLE]# lvchange -an vg/lv; lvchange -ay vg/lv; lvs vg
  LV   VG   Attr     LSize Pool Origin Snap%  Move Log Copy%  Convert
  lv   vg   Mwi-a-m- 5.00g                               0.08
[EXAMPLE]# lvextend -L +5G vg/lv
  Extending 2 mirror images.
  Extending logical volume lv to 10.00 GiB
  vg/lv cannot be extended while it is recovering.

7) If 'no' is selected in #5 or if the condition in #6 is hit, it should not
result in the mirror being resized or the 'm/M' attribute being changed.


NOTE:  A mirror created with '--nosync' behaves differently than one created
without it when performing an extension.  The former cannot be extended when
the mirror is recovering (unless in-active), while the latter can.  This is
a reasonable thing to do since recovery of a mirror doesn't take long (at
least in the case of an on-disk log) and it would cause far more time in
degraded mode if the extension w/o '--nosync' was allowed.  It might be
reasonable to add the ability to force the operation in the future.  This
should /not/ force a nosync extension, but rather force a sync'ed extension.
IOW, the user would be saying, "Yes, yes... I know recovery won't take long
and that I'll be adding significantly to the time spent in degraded mode, but
I need the extra space right now!".
2011-10-06 15:32:26 +00:00
..
activate Fix splitmirror in cluster having different DM/LVM views of storage. 2011-10-06 14:55:39 +00:00
cache Use size_t return type 2011-09-01 10:25:22 +00:00
commands Add activation/retry_deactivation to lvm.conf to retry deactivation of an LV. 2011-09-22 17:39:56 +00:00
config Add activation/retry_deactivation to lvm.conf to retry deactivation of an LV. 2011-09-22 17:39:56 +00:00
datastruct Revert the #include changes. Need to fix this at the #include site for now, and 2011-07-18 14:34:33 +00:00
device Move the core of the lib/config/config.c functionality into libdevmapper, 2011-08-30 14:55:15 +00:00
display Use capital letters 2011-10-04 12:39:59 +00:00
error Add lv_activate_opts structure 2011-06-17 14:14:19 +00:00
filters Move the core of the lib/config/config.c functionality into libdevmapper, 2011-08-30 14:55:15 +00:00
format1 lvcreate parsing for thin provisioning. 2011-09-06 00:26:42 +00:00
format_pool lvcreate parsing for thin provisioning. 2011-09-06 00:26:42 +00:00
format_text lvcreate/remove thin_pool and thin volumes (--driverloaded n only) 2011-09-08 16:41:18 +00:00
freeseg Replace malloc with zalloc when creating segment_type's 2011-03-25 21:59:42 +00:00
label Report sector containing label in verbose message. 2011-06-01 15:30:36 +00:00
locking Introduce revert_lv for better pvmove cleanup. 2011-09-27 22:43:40 +00:00
log Trivial, add void to ignore dm_snprinf result 2011-08-11 19:21:42 +00:00
metadata Allow 'nosync' extension of mirrors. 2011-10-06 15:32:26 +00:00
mirror Replace const usage of dm_config_find_node with more appropriate value-lookup 2011-08-31 15:19:19 +00:00
misc Add activation/retry_deactivation to lvm.conf to retry deactivation of an LV. 2011-09-22 17:39:56 +00:00
mm Move the core of the lib/config/config.c functionality into libdevmapper, 2011-08-30 14:55:15 +00:00
raid Fix log_error() usage 2011-09-24 21:19:30 +00:00
replicator Move the core of the lib/config/config.c functionality into libdevmapper, 2011-08-30 14:55:15 +00:00
report correct thin_pool width 2011-09-27 12:33:36 +00:00
snapshot Move the core of the lib/config/config.c functionality into libdevmapper, 2011-08-30 14:55:15 +00:00
striped Replace const usage of dm_config_find_node with more appropriate value-lookup 2011-08-31 15:19:19 +00:00
thin Add more validation to config parser 2011-10-06 11:06:36 +00:00
unknown Fix log_error() usage 2011-09-24 21:19:30 +00:00
uuid Revert the #include changes. Need to fix this at the #include site for now, and 2011-07-18 14:34:33 +00:00
zero Add lv_activate_opts structure 2011-06-17 14:14:19 +00:00
Makefile.in add thin_manip.c like the other manip files 2011-09-06 19:25:42 +00:00