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authorJonathan Earl Brassow <jbrassow@redhat.com>2011-10-06 15:32:26 +0000
committerJonathan Earl Brassow <jbrassow@redhat.com>2011-10-06 15:32:26 +0000
commita80192b6a7dcb08224db1e2623fc6c5d5b9975f4 (patch)
tree5c563d27cacc5403259fdddf326636dd14d3dfa0 /tools/lvresize.c
parentb19f01212e3bf47b6d41568b0b3567106c87f99b (diff)
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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!".
Diffstat (limited to 'tools/lvresize.c')
-rw-r--r--tools/lvresize.c7
1 files changed, 7 insertions, 0 deletions
diff --git a/tools/lvresize.c b/tools/lvresize.c
index 96e623e1..f4b81da3 100644
--- a/tools/lvresize.c
+++ b/tools/lvresize.c
@@ -504,6 +504,13 @@ static int _lvresize(struct cmd_context *cmd, struct volume_group *vg,
/* If extending, find mirrors of last segment */
if ((lp->extents > lv->le_count)) {
+ /*
+ * Has the user specified that they would like the additional
+ * extents of a mirror not to have an initial sync?
+ */
+ if (seg_is_mirrored(first_seg(lv)) && arg_count(cmd, nosync_ARG))
+ lv->status |= LV_NOTSYNCED;
+
dm_list_iterate_back_items(mirr_seg, &lv->segments) {
if (seg_is_mirrored(mirr_seg))
seg_mirrors = lv_mirror_count(mirr_seg->lv);