diff options
| author | mulhern <amulhern@redhat.com> | 2017-11-27 16:02:39 +0100 |
|---|---|---|
| committer | Mike Snitzer <snitzer@redhat.com> | 2018-01-17 15:16:10 +0100 |
| commit | 9b28a1102efc75d81298198166ead87d643a29ce (patch) | |
| tree | 68d764d3f4181bf41f3570775c8706ced97059e1 /Documentation/device-mapper | |
| parent | dm cache: be consistent in specifying sectors and SI units in cache.txt (diff) | |
| download | linux-9b28a1102efc75d81298198166ead87d643a29ce.tar.xz linux-9b28a1102efc75d81298198166ead87d643a29ce.zip | |
dm thin: fix documentation relative to low water mark threshold
Fixes:
1. The use of "exceeds" when the opposite of exceeds, falls below,
was meant.
2. Properly speaking, a table can not exceed a threshold.
It emphasizes the important point, which is that it is the userspace
daemon's responsibility to check for low free space when a device
is resumed, since it won't get a special event indicating low free
space in that situation.
Signed-off-by: mulhern <amulhern@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Diffstat (limited to 'Documentation/device-mapper')
| -rw-r--r-- | Documentation/device-mapper/thin-provisioning.txt | 8 |
1 files changed, 5 insertions, 3 deletions
diff --git a/Documentation/device-mapper/thin-provisioning.txt b/Documentation/device-mapper/thin-provisioning.txt index 1699a55b7b70..ef639960b272 100644 --- a/Documentation/device-mapper/thin-provisioning.txt +++ b/Documentation/device-mapper/thin-provisioning.txt @@ -112,9 +112,11 @@ $low_water_mark is expressed in blocks of size $data_block_size. If free space on the data device drops below this level then a dm event will be triggered which a userspace daemon should catch allowing it to extend the pool device. Only one such event will be sent. -Resuming a device with a new table itself triggers an event so the -userspace daemon can use this to detect a situation where a new table -already exceeds the threshold. + +No special event is triggered if a just resumed device's free space is below +the low water mark. However, resuming a device always triggers an +event; a userspace daemon should verify that free space exceeds the low +water mark when handling this event. A low water mark for the metadata device is maintained in the kernel and will trigger a dm event if free space on the metadata device drops below |