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man lvmsystemid: update changing the system_id

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This commit is contained in:
David Teigland 2015-02-20 16:55:27 -06:00
parent cfd1b8eae2
commit 42ba7974c5
1 changed files with 18 additions and 11 deletions
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man/lvmsystemid.7.in
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@ -5,10 +5,10 @@ lvmsystemid \(em LVM system id
.SH DESCRIPTION .SH DESCRIPTION
Local VG's may exist on shared storage where they are visible to multiple Local VGs may exist on shared storage where they are visible to multiple
hosts. These VG's are intended to be used by only a single machine, even hosts. These VGs are intended to be used by only a single machine, even
though they are visible to many. A system_id identifying a single host though they are visible to many. A system_id identifying a single host
can be assigned to a VG to indicate the VG's owner. The VG owner can use can be assigned to a VG to indicate the VGs owner. The VG owner can use
the VG as usual, and all other hosts will ignore it. This protects the VG the VG as usual, and all other hosts will ignore it. This protects the VG
from accidental use by other hosts. from accidental use by other hosts.
@ -29,7 +29,7 @@ A VG without a system_id can be used by any host, and a VG with a
system_id can only be used by a host with a matching system_id. A system_id can only be used by a host with a matching system_id. A
.B foreign VG .B foreign VG
is a VG with a system_id as viewed by a host with a system_id is a VG with a system_id as viewed by a host with a system_id
that does not match the VG's system_id. (Or from a host without a that does not match the VGs system_id. (Or from a host without a
system_id.) system_id.)
Valid system_id characters are the same as valid VG name characters. If a Valid system_id characters are the same as valid VG name characters. If a
@ -236,8 +236,9 @@ devices.
The system_id of a VG is displayed with the "systemid" reporting option. The system_id of a VG is displayed with the "systemid" reporting option.
Report/display commands ignore foreign VGs by default. To report foreign Report/display commands ignore foreign VGs by default. To report foreign
VGs, the --foreign option can be used. This causes all VGs to be read VGs, the --foreign option can be used. This causes the VGs to be read
from disk. from disk. Because lvmetad caching is not used, this option can cause
poor performance.
.B vgs --foreign -o+systemid .B vgs --foreign -o+systemid
@ -265,16 +266,22 @@ imported VG as foreign.
.SS vgchange .SS vgchange
If a VG has a system_id, changing it with vgchange requires --force. A host can change the system_id of its own VGs, but the command requires
vgchange --systemid is accepted just as with vgcreate. confirmation because the host may lose access to the VG being changed:
If a host's system_id is changed, the system_id of its own VG's can be .B vgchange --systemid
changed to match. Using allow_system_id is a way to avoid using force .I SystemID VG
with vgchange.
A host cannot directly change the system_id of a foreign VG.
To move a VG from one host to another, vgexport and vgimport should be To move a VG from one host to another, vgexport and vgimport should be
used. used.
To forcibly gain ownership of a foreign VG, a host can add the foreign
system_id to its allow_system_id list, change the system_id of the foreign
VG to its own, and remove the foreign system_id from its allow_system_id
list.
.SS clustered VGs .SS clustered VGs
A "clustered" VG should have no system_id set, allowing multiple hosts to A "clustered" VG should have no system_id set, allowing multiple hosts to