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commit 4c5b67d68b8207f95cd35e30d5ff193b6ac6be12 Author: Alexey Serbin <[email protected]> AuthorDate: Fri Aug 27 19:48:22 2021 -0700 [docs] add info on quick hole punching test Change-Id: Ibac1af744bb163144d6c19d9e0f1aac3b5fba6e9 Reviewed-on: http://gerrit.cloudera.org:8080/17814 Tested-by: Kudu Jenkins Reviewed-by: Andrew Wong <[email protected]> --- docs/troubleshooting.adoc | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/docs/troubleshooting.adoc b/docs/troubleshooting.adoc index 95a572f..8433a16 100644 --- a/docs/troubleshooting.adoc +++ b/docs/troubleshooting.adoc @@ -68,6 +68,19 @@ Exchange post] for details. Without hole punching support, the log block manager is unsafe to use. It won't ever delete blocks, and will consume ever more space on disk. +You can run the following sequence of commands on a mounted file system to +check whether it supports hole punching (the originally allocated 10MiB +turns into 5MiB after punching a 5MiB hole in the file at 1MiB offset): + +---- +$ dd if=/dev/zero of=hole_punch bs=1M count=10 2>/dev/null +$ du -h hole_punch +10M hole_punch +$ fallocate -p -o 1M -l 5M hole_punch +$ du -h hole_punch +5.0M hole_punch +---- + If you can't use hole punching in your environment, you can still try Kudu. Enable the file block manager instead of the log block manager by adding the `--block_manager=file` flag to the commands you use to start the master
