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Routines responsible for polling of in-progress pvmove, snapshot merge
or mirror conversion each used custom lookup functions to find vg and
lv involved in polling.
Especially pvmove used pvname to lookup pvmove in-progress. The future
lvmpolld will poll each operation by vg/lv name (internally by lvid).
Also there're plans to make pvmove able to move non-overlaping ranges
of extents instead of single PVs as of now. This would also require
to identify the opertion in different manner.
The poll_operation_id structure together with daemon_parms structure they
identify unambiguously the polling task.
So far pvmove_update_metadata (originaly _update_metadata) was
used for both initial and subsequent metadata updates during polling.
With a new polldaemon (lvmpolld) all operations that require polling
have to be split in two parts: The initiating one and the polling one.
The later step will be used from lvm command spawned by lvmpolld to
monitor and advance the mirror on next segment if required.
1) The initiation part is _update_metadata in pvmove.c which performs
only the first update, setting up the pvmove itself in metadata.
2) pvmove_update_metadata in pvmove_poll.c now handles all other
subsequent metadata updates except the last one.
Due to the split we could remove some code. Also some functions were
moved back to pvmove.c as they were suited for initialisation of pvmove
only.
This commit has no impact on functionality. Code required to
be visible outside pvmove.c is just moved into new file
pvmove_poll.c and some calls are made non-static and declared in
new header file pvmove.h
Try to enforce consistent macro usage along these lines:
lv_is_mirror - mirror that uses the original dm-raid1 implementation
(segment type "mirror")
lv_is_mirror_type - also includes internal mirror image and log LVs
lv_is_raid - raid volume that uses the new dm-raid implementation
(segment type "raid")
lv_is_raid_type - also includes internal raid image / log / metadata LVs
lv_is_mirrored - LV is mirrored using either kernel implementation
(excludes non-mirror modes like raid5 etc.)
lv_is_pvmove - internal pvmove volume
Use lv_is_* macros throughout the code base, introducing
lv_is_pvmove, lv_is_locked, lv_is_converting and lv_is_merging.
lv_is_mirror_type no longer includes pvmove.
With cmirrord, we can do pvmove of clustered mirror. The code checking
suitability of LVs on the PV being moved issued a message if a mirror
LV was found and the VG was clustered. However, the actual pvmove did
work correctly.
The top-level mirror LV is actually skipped in the code since it's
always layered on top of internal LVs making up the mirror LV and for pvmove
we consider these internal devices only as they're actually layered on
top of concrete PVs then. But we don't need to issue any message here
about skipping the top-level mirror LV - it's misleading here.
pvmove can be used to move single LVs by name or multiple LVs that
lie within the specified PV range (e.g. /dev/sdb1:0-1000). When
moving more than one LV, the portions of those LVs that are in the
range to be moved are added to a new temporary pvmove LV. The LVs
then point to the range in the pvmove LV, rather than the PV
range.
Example 1:
We have two LVs in this example. After they were
created, the first LV was grown, yeilding two segments
in LV1. So, there are two LVs with a total of three
segments.
Before pvmove:
--------- --------- ---------
| LV1s0 | | LV2s0 | | LV1s1 |
--------- --------- ---------
| | |
-------------------------------------
PV | 000 - 255 | 256 - 511 | 512 - 767 |
-------------------------------------
After pvmove inserts the temporary pvmove LV:
--------- --------- ---------
| LV1s0 | | LV2s0 | | LV1s1 |
--------- --------- ---------
| | |
-------------------------------------
pvmove0 | seg 0 | seg 1 | seg 2 |
-------------------------------------
| | |
-------------------------------------
PV | 000 - 255 | 256 - 511 | 512 - 767 |
-------------------------------------
Each of the affected LV segments now point to a
range of blocks in the pvmove LV, which purposefully
corresponds to the segments moved from the original
LVs into the temporary pvmove LV.
The current implementation goes on from here to mirror the temporary
pvmove LV by segment. Further, as the pvmove LV is activated, only
one of its segments is actually mirrored (i.e. "moving") at a time.
The rest are either complete or not addressed yet. If the pvmove
is aborted, those segments that are completed will remain on the
destination and those that are not yet addressed or in the process
of moving will stay on the source PV. Thus, it is possible to have
a partially completed move - some LVs (or certain segments of LVs)
on the source PV and some on the destination.
Example 2:
What 'example 1' might look if it was half-way
through the move.
--------- --------- ---------
| LV1s0 | | LV2s0 | | LV1s1 |
--------- --------- ---------
| | |
-------------------------------------
pvmove0 | seg 0 | seg 1 | seg 2 |
-------------------------------------
| | |
| -------------------------
source PV | | 256 - 511 | 512 - 767 |
| -------------------------
| ||
-------------------------
dest PV | 000 - 255 | 256 - 511 |
-------------------------
This update allows the user to specify that they would like the
pvmove mirror created "by LV" rather than "by segment". That is,
the pvmove LV becomes an image in an encapsulating mirror along
with the allocated copy image.
Example 3:
A pvmove that is performed "by LV" rather than "by segment".
--------- ---------
| LV1s0 | | LV2s0 |
--------- ---------
| |
-------------------------
pvmove0 | * LV-level mirror * |
-------------------------
/ \
pvmove_mimage0 / pvmove_mimage1
------------------------- -------------------------
| seg 0 | seg 1 | | seg 0 | seg 1 |
------------------------- -------------------------
| | | |
------------------------- -------------------------
| 000 - 255 | 256 - 511 | | 000 - 255 | 256 - 511 |
------------------------- -------------------------
source PV dest PV
The thing that differentiates a pvmove done in this way and a simple
"up-convert" from linear to mirror is the preservation of the
distinct segments. A normal up-convert would simply allocate the
necessary space with no regard for segment boundaries. The pvmove
operation must preserve the segments because they are the critical
boundary between the segments of the LVs being moved. So, when the
pvmove copy image is allocated, all corresponding segments must be
allocated. The code that merges ajoining segments that are part of
the same LV when the metadata is written must also be avoided in
this case. This method of mirroring is unique enough to warrant its
own definitional macro, MIRROR_BY_SEGMENTED_LV. This joins the two
existing macros: MIRROR_BY_SEG (for original pvmove) and MIRROR_BY_LV
(for user created mirrors).
The advantages of performing pvmove in this way is that all of the
LVs affected can be moved together. It is an all-or-nothing approach
that leaves all LV segments on the source PV if the move is aborted.
Additionally, a mirror log can be used (in the future) to provide tracking
of progress; allowing the copy to continue where it left off in the event
there is a deactivation.
Skip over LVs that have a cache LV in their tree of LV dependencies
when performing a pvmove.
This means that users cannot move a cache pool or a cache LV's origin -
even when that cache LV is used as part of another LV (e.g. a thin pool).
The new test (pvmove-cache-segtypes.sh) currently builds up various LV
stacks that incorporate cache LVs. pvmove tests are then performed to
ensure that cache related LVs are /not/ moved. Once pvmove is enabled
for cache, those tests will switch to ensuring that the LVs /are/
moved.
Replacement of pv_read by find_pv_by_name in commit
651d5093ed caused spurious
error messages when running pvcreate or vgextend against an
unformatted device.
Physical volume /dev/loop4 not found
Physical volume "/dev/loop4" successfully created
Physical volume /dev/loop4 not found
Physical volume /dev/loop4 not found
Physical volume "/dev/loop4" successfully created
Volume group "vg1" successfully extended
The patch allows the user to also pvmove snapshots and origin logical
volumes. This means pvmove should be able to move all segment types.
I have, however, disallowed moving converting or merging logical volumes.
Top-level LVs (like RAID, mirror or thin) are ignored when determining which
portions of an LV to pvmove. If the user specified the name of an LV to
move and it was one of the above types, it would be skipped. The code would
never move on to check whether its sub-LVs needed moving because their names
did not match what the user specified.
The solution is to check whether a sub-LVs is part of the LV whose name was
specified by the user - not just if there was a name match.
This patch allows pvmove to operate on RAID, mirror and thin LVs.
The key component is the ability to avoid moving a RAID or mirror
sub-LV onto a PV that already has another RAID sub-LV on it.
(e.g. Avoid placing both images of a RAID1 LV on the same PV.)
Top-level LVs are processed to determine which PVs to avoid for
the sake of redundancy, while bottom-level LVs are processed
to determine which segments/extents to move.
This approach does have some drawbacks. By eliminating whole PVs
from the allocation list, we might miss the opportunity to perform
pvmove in some senarios. For example, if we have 3 devices and
a linear uses half of the first, a RAID1 uses half of the first and
half of the second, and a linear uses half of the third (FIGURE 1);
we should be able to pvmove the first device (FIGURE 2).
FIGURE 1:
[ linear ] [ -RAID- ] [ linear ]
[ -RAID- ] [ ] [ ]
FIGURE 2:
[ moved ] [ -RAID- ] [ linear ]
[ moved ] [ linear ] [ -RAID- ]
However, the approach we are using would eliminate the second
device from consideration and would leave us with too little space
for allocation. In these situations, the user does have the ability
to specify LVs and move them one at a time.
Before, the find_pv_by_name call always failed if the PV found was orphan.
However, we might use this function even for a PV that is not part of any VG.
This patch adds 'allow_orphan' arg to find_pv_by_name fn that allows that.
Attempting pvmove on RAID LVs replaces the kernel RAID target with
a temporary pvmove target, ultimately destroying the RAID LV. pvmove
must be prevented on RAID LVs for now.
Use 'lvconvert --replace old_pv vg/lv new_pv' if you want to move
an image of the RAID LV.
Accept -q as the short form of --quiet.
Suppress non-essential standard output if -q is given twice.
Treat log/silent in lvm.conf as equivalent to -qq.
Review all log_print messages and change some to
log_print_unless_silent.
When silent, the following commands still produce output:
dumpconfig, lvdisplay, lvmdiskscan, lvs, pvck, pvdisplay,
pvs, version, vgcfgrestore -l, vgdisplay, vgs.
[Needs checking.]
Non-essential messages are shifted from log level 4 to log level 5
for syslog and lvm2_log_fn purposes.
locally or on more nodes while others are activated exclusively.
Current pvmove code can either use local mirror (for exclusive
activation) or cmirror (for clustered LVs).
Because the whole intenal pvmove LV is just segmented LV containing
segments of several top-level LVs, code cannot properly handle
situation if some segment need to be activated exclusively.
Previously, it wrongly activated exclusive LV on all nodes
(locing code allowed it) but now this is no lnger possible.
If there is exclusively activated LV, pvmove is only
possible if all affected LVs are aslo activated exclusively.
(Note that in non-exclusive mode pvmove still activates LVs
on other nodes during move.)
# lvchange -aly vg_test/lv1
# lvchange -aey vg_test/lv2
# pvmove -i 1 /dev/sdc
Error locking on node bar-01: Device or resource busy
Error locking on node bar-03: Volume is busy on another node
...
Failed to activate lv2
Workaround for the current code with big FIXME,
since proper solution for pvmove needs to be developed.
Commiting this only for the purpose to get cluster testing covered.
leaving behind the LVM-specific parts of the code (convenience wrappers that
handle `struct device` and `struct cmd_context`, basically). A number of
functions have been renamed (in addition to getting a dm_ prefix) -- namely,
all of the config interface now has a dm_config_ prefix.
Move the free_vg() to vg.c and replace free_vg with release_vg
and make the _free_vg internal.
Patch is needed for sharing VG in vginfo cache so the release_vg function name
is a better fit here.
are affected by the move. (Currently it's possible for I/O to become
trapped between suspended devices amongst other problems.
The current fix was selected so as to minimise the testing surface. I
hope eventually to replace it with a cleaner one that extends the
deptree code.
Some lvconvert scenarios still suffer from related problems.
Since format instances will use own memory pool, it's necessary to properly
deallocate it. For now, only fid is deallocated. The PV structure itself
still uses cmd mempool mostly, but anytime we'd like to add a mempool
in the struct physical_volume, we can just rename this fn to free_pv and
add the code (like we have free_vg fn for VGs).
If pvmove crashed and metadata contains pvmove LV
but without miorrored segments, pvmove --abort
will not repair the situation (and finish wth success!).
Fix it by allowing metadata update if aborting
(thus removing pvmove LV) even if no moved LVs detected.
(Tested on real metadata provided by an lvm user:-)
