doc/ceph-bluestore-tool: add description for show-label-at command.

Signed-off-by: Igor Fedotov <igor.fedotov@croit.io>
(cherry picked from commit 4f5f8483444e4fa16939d917ca5e42120e7ccbc9)

diff --git a/doc/man/8/ceph-bluestore-tool.rst b/doc/man/8/ceph-bluestore-tool.rst
index 7e9e3b2e8df0a9a8f0e929aa68d2b8add6a3964f..f97fe76621a14d35f5f89cba99ca3e0f7615a29d 100644 (file)
--- a/doc/man/8/ceph-bluestore-tool.rst
+++ b/doc/man/8/ceph-bluestore-tool.rst
@@ -21,6 +21,7 @@ Synopsis
 | **ceph-bluestore-tool** allocmap    --path *osd path*
 | **ceph-bluestore-tool** restore_cfb --path *osd path*
 | **ceph-bluestore-tool** show-label --dev *device* ...
+| **ceph-bluestore-tool** show-label-at --dev *device* --offset *lba*...
 | **ceph-bluestore-tool** prime-osd-dir --dev *device* --path *osd path*
 | **ceph-bluestore-tool** bluefs-export --path *osd path* --out-dir *dir*
 | **ceph-bluestore-tool** bluefs-bdev-new-wal --path *osd path* --dev-target *new-device*
@@ -111,6 +112,13 @@ Commands
    Show device label(s).
    The label may be printed while an OSD is running.
 
+:command:`show-label-at` --dev *device* --offset *lba*[...]
+
+   Show device label at specific disk location. Dedicated DB/WAL volumes have a single label at offset 0.
+   Main device could have valid labels at multiple locations: 0/1GiB/10GiB/100GiB/1000GiB.
+   The labels at some locations might not exist though. 
+   The label may be printed while an OSD is running.
+
 :command:`free-dump` --path *osd path* [ --allocator block/bluefs-wal/bluefs-db/bluefs-slow ]
 
    Dump all free regions in allocator.
@@ -201,6 +209,8 @@ Device labels
 =============
 
 Every BlueStore block device has a block label at the beginning of the device.
+Main device might optionaly have additional labels at different locations
+for the sake of OSD robustness.
 You can dump the contents of the label with::
 
   ceph-bluestore-tool show-label --dev *device*
@@ -209,7 +219,7 @@ The main device will have a lot of metadata, including information
 that used to be stored in small files in the OSD data directory.  The
 auxiliary devices (db and wal) will only have the minimum required
 fields (OSD UUID, size, device type, birth time).
-The main device contains additional label copies at offsets: 1G, 10G, 100G and 1000G.
+The main device contains additional label copies at offsets: 1GiB, 10GiB, 100GiB and 1000GiB.
 Corrupted labels are fixed as part of repair::
 
   ceph-bluestore-tool repair --dev *device*