On 10.05.2018 12:24, Yi-Cian Pu wrote:
Hi All,
We are wondering if there is any way to expand OSD’s capacity. We are
studying about this and conducted an experiment. However, in the
result, the size of expanded capacity is counted on the USED part
rather than the AVAIL one. The following shows the process of our
experiment:
1.We prepare a small cluster of luminous v12.2.4 and write some data
into pool. The osd.1 is manually deployed and it uses a disk partition
of size 100GB (the whole disk size is 320GB).
=====================================================================
[root@workstation /]# ceph osd df
ID CLASS WEIGHTREWEIGHT SIZE USEAVAIL%USEVARPGS
0hdd 0.289991.00000 297G 27062M271G8.89 0.6732
1hdd 0.099991.00000 100G 27062M 76361M 26.17 1.9732
TOTAL 398G 54125M345G 13.27
MIN/MAX VAR: 0.67/1.97STDDEV: 9.63
=====================================================================
2.Then, we expand the disk partition used by osd.1 by the following steps:
(1)Stop osd.1 daemon
(2)Use “parted” command to expand 50GB of the disk partition.
(3)Restart osd.1 daemon
3.After we do the above steps, we have the result that the expanded
size is counted on USED part.
=====================================================================
[root@workstation /]# ceph osd df
ID CLASS WEIGHTREWEIGHT SIZE USEAVAIL%USEVARPGS
0hdd 0.289991.00000 297G 27063M271G8.89 0.3932
1hdd 0.099991.00000 150G 78263M 76360M 50.62 2.2132
TOTAL 448G102G345G 22.94
MIN/MAX VAR: 0.39/2.21STDDEV: 21.95
=====================================================================
This is what we have tried, and the result looks very confusing. We’d
really want to
know if there is any way to normally expand OSD’s capacity. Any
feedback or suggestions would be much appreciated.
you do not do this in ceph
you would most likely not partition the osd drive, you use the whole
drive. so you would never get into the position to need to increase.
you add space by adding osd's and adding nodes, so increasing osd size
is not logical
if you must for some oddball reason... you can remove (drain or
destroy) - repartition - add the osd and let ceph backfill the drive.
or you can just make a new osd with the remaining disk space.
since the space increase will change the crushmap there is no way to
avoid some data movement, anyway.
mvh
Ronny Aasen
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