Bug 1855804

Problems with examples (***suggestions*** can be found on the same line as the problem):

3. Change default setting used for creating VDOPoolLV
       Example
       # cat <<EOF > vdo.profile    ***cat <<EOF > /etc/lvm/profile/vdo.profile***
       allocation {
            vdo_use_compression=1
            vdo_use_deduplication=1
            vdo_use_metadata_hints=1
            vdo_minimum_io_size=4096
            vdo_block_map_cache_size_mb=128
            vdo_block_map_period=16380
            vdo_check_point_frequency=0
            vdo_use_sparse_index=0
            vdo_index_memory_size_mb=256
            vdo_slab_size_mb=2048
            vdo_ack_threads=1
            vdo_bio_threads=1
            vdo_bio_rotation=64
            vdo_cpu_threads=2
            vdo_hash_zone_threads=1
            vdo_logical_threads=1
            vdo_physical_threads=1
            vdo_write_policy="auto"
            vdo_max_discard=1
       }
       EOF

       # lvcreate --vdo -L10G --metadataprofile vdo.profile vg/vdopool0    ***lvcreate --vdo -L10G --metadataprofile vdo vg/vdopool0***
       # lvcreate --vdo -L10G --config 'allocation/vdo_cpu_threads=4' vg/vdopool1

4. Checking usage of VDOPoolLV
       Example
       # lvcreate --type vdo -L10G -V20G -n vdo0 vg/vdopool0
       # mkfs.ext4 -E nodiscard /dev/vg/vdo0
       # lvs -a vg

         LV               VG Attr       LSize  Pool     Origin Data%
         vdo0             vg vwi-a-v--- 20.00g vdopool0        0.01
         vdopool0         vg dwi-ao---- 10.00g                 30.16
         [vdopool0_vdata] vg Dwi-ao---- 10.00g

       # vdostats --all /dev/mapper/vg-vdopool0    ***vdostats --all /dev/mapper/vg-vdopool0-vpool***
       /dev/mapper/vg-vdopool0 :
         version                             : 30
         release version                     : 133524
         data blocks used                    : 79
         ...

3. Caching VDOLV
       Example
       # lvcreate -L 5G -V 10G -n vdo1 vg/vpool    ***lvcreate --type vdo -L 5G -V 10G -n vdo1 vg/vpool***
       # lvcreate --type cache-pool -L 1G -n cpool vg
       # lvconvert --cache --cachepool vg/cpool vg/vdo1
       # lvconvert --uncache vg/vdo1

Pushed updates for man pages:

https://www.redhat.com/archives/lvm-devel/2020-August/msg00013.html

Mostly fixes reported issue from BZ description - although some capital
letters remained to be more look a like to other man pages
(as there is no real strick guide how to use them)

Comment 1 need another look - the thing to note is - that it's
been rather illustratively written - but if it doesn't
really work - then it might some polishing and doc enhancements.

Upstreamed remaining issues from comment 1:

https://www.redhat.com/archives/lvm-devel/2020-September/msg00045.html

with few more 'configure' based updates.
https://www.redhat.com/archives/lvm-devel/2020-September/msg00045.html


If there will be chance to squeeze them into a release - these patches have zero risk.

Fixes referenced in comment #2 and comment #4 looks good.

However I seems issues num. 3, 4, 5, 11 and 13 from the bug description haven't been fixed. Could you, please, provide a reason why they are not fixed?

'man lvmvdo' states that kvdo (refers to kmod-kvdo package) is required, however that's not completely true because without 'vdo' package lvcreate fails:

# rpm -qa  |grep vdo
kmod-kvdo-6.2.4.14-74.el8.x86_64

# lvcreate --type vdo -L10G -V100G -n vdovol vg
  /usr/bin/vdoformat: execvp failed: No such file or directory
  Command /usr/bin/vdoformat failed.
  Cannot format VDO pool volume vg/vpool0.

# yum install -y vdo
...

# lvcreate --type vdo -L10G -V100G -n vdovol vg
    The VDO volume can address 6 GB in 3 data slabs, each 2 GB.
    It can grow to address at most 16 TB of physical storage in 8192 slabs.
    If a larger maximum size might be needed, use bigger slabs.
  Logical volume "vdovol" created.

If you'd like the man page to be reviewed by a technical writer, let me know.

Pushed update: https://www.redhat.com/archives/lvm-devel/2020-November/msg00000.html

3,4,5 rephrased
11 changed
13 added more info

Also added 2 new chapters about memory and space usage.

Fixed some cpool & vpool names in examples

More condensed page by dropping unneded empty lines.

Due to impediments in delivery of related test compose I'm increasing ITM to 5.

Tested on lvm2-2.03.11-0.2.20201103git8801a86.el8.x86_64; build RHEL-8.4.0-20201110.d.3:

* Almost all the problems were fixed - unfortunately the last problem from comment #1 (3. Caching VDOLV) is still not fixed.
* The overall quality of the manpage seems to me greatly improved.
* Marking this bug as verified:tested and passing the manpage for review by msuchane.

pkg: lvm2-2.03.11-0.2.20201103git8801a86.el8.x86_64
distro: RHEL-8.4.0-20201201.n.1

Unfortunately, despite of fixes and overall improvements not all the issues are fixed:

* last problem from comment #1 (3. Caching VDOLV) is still not fixed,
* patch mentioned in comment #20 with language and style edits doesn't seem to be applied,
* ambiguities mentioned in review by Marek Suchanek [0] are not resolved.

Therefore I cannot consider this bug as fixed.


[0] https://docs.google.com/document/d/1iHTUXzeAEZK1eO81uAEOFickh2kMgG5IiALqq6oJWvw/edit

Upstream patch:  https://www.redhat.com/archives/lvm-devel/2020-December/msg00000.html
likely missed inclusion into build?

Pushed some more tunings for comment 21.

https://www.redhat.com/archives/lvm-devel/2020-December/msg00002.html

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory (lvm2 bug fix and enhancement update), and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHBA-2021:1659