5 Commits

Author	SHA1	Message	Date
Jonathan Brassow	5ebff6cc9f	pvmove: Enable all-or-nothing (atomic) pvmoves ... 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.	2014-06-17 22:59:36 -05:00
Zdenek Kabelac	5c5177c37c	tests: rename test to inittest ... We are getting into problem when we use 'test' for commands like should/not/... So avoid overloading test name and change it to inittest.	2014-06-10 10:51:27 +02:00
Zdenek Kabelac	2e9792121f	tests: add have_cache and have_raid ... Need to be aware of build options, when system would be configure without raid or cache support	2014-05-20 21:50:30 +02:00
Zdenek Kabelac	47b15b805e	tests: updates ... Add some vgremove calls. Remove uneeded test for some unused commands. Add tests for missing commands.	2014-02-27 13:01:04 +01:00
Zdenek Kabelac	fbb732bd8e	tests: enhance pvmove testing ... Rewrite check lv_on and add new lv_tree_on Move more pvmove test unrelated code out to check & get sections (so they do not obfuscate trace output unnecesserily) Use new lv_tree_on() NOTE: unsure how the snapshot origin should be accounted here. Split pmove-all-segments into separate tests for raid and thins (so the test output properly shows what has been skipped in test)	2013-09-16 11:22:04 +02:00