Difference between revisions of "Btrfs/tr"

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-Don´t forget to remove snapshots, or you will get in '''[[Btrfs#Out_of_space|out of space]]-trouble soon'''. Btrfs needs some free space to manage its work. If your volume is more then 85% full you have to think(fast) what to do.
+Don't forget to delete snapshots, or you'll soon run into '''[[Btrfs#Out_of_space|out of space]] problems'''. Btrfs needs free space (at least 5 GB) to do its work. If your volume is more than 90% full, you'll need to figure out what to do (quickly). Even a Manjaro update can be more than 10 GB in size, so you'll always need some free space.
 * ++++ '''[[Btrfs#Extend_a_volume|Add]]''' some partition/device to the volume
-* +++ '''Remove''' some snapshots you don't need
+* +++ '''Remove''' some snapshots you don't need (starting with the oldest one!)
 * ++ [[Btrfs#Compression_.E2.87.92|Compress]] your volume
 * + '''Delete''' some files (This does only help if they are not part of '''any''' snapshot)
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 Please also have a look at [https://github.com/jrabinow/snapper-rollback snapper-rollback@github] and at [https://wiki.archlinux.org/title/Snapper#Suggested_filesystem_layout snapshot-layout@wiki.archlinux] for the suggested flat layout and the reasoning. ([https://forum.manjaro.org/t/how-to-manual-rollback-with-btrfs/80230 Rollback example ])
-{{BoxWarning|Don't forget to remove snapshots before you run out of space|Every time you take a snapshot you only use the "rest of the volume" for storing everything you change from this time on. At some point in time you have to release the snapshot. Don´t use your space up. Btrfs needs '''space to breath.''' Don't use more then '''90%''' or you will get deep into trouble."}}
+{{BoxWarning|Don't forget to delete snapshots before you run out of space|Each time you create a snapshot, you only use the '''rest of the volume''' to save all changes. Eventually, you'll need to free the snapshot. Don't overuse the space. Btrfs needs '''breathing room.''' Don't use more than '''95%''' and leave at least '''5 GB free''', or you'll be in big trouble.}}
 {{BoxDanger|NO Snapshots together with quotas|There are reports about massive problems when using '''quotas''' together with snapshots (snapper, timeshift). Please have a look at: [https://btrfs.wiki.kernel.org/index.php/Quota_support#Known_issues Known_issues@btrfs.kernel.org]}}
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 * '''balance''' all chunks that are less than 90% full. This '''will''' take some time !
 {{RootCmd|command=btrfs balance start -dusage=90 /}}
-{{BoxWarning|Don't use filters higher than 90%|This is unnecessary on an SSD drive. On a hard drive, this will put a lot of strain on the disk. Even with today's hard drives (>2TB), it may take a very long time. (e.g. 24 hours or more)}}
+{{BoxWarning|Don't use filters higher than 95%|This is unnecessary on an SSD drive. On a hard drive, this will put a lot of strain on the disk. Even with today's hard drives (>2TB), it may take a very long time. (e.g. 24 hours or more)}}
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 === Merging chunks ===
-As you use your volume, you will be creating some files, deleting some, modifying some. Then some parts of the chunks are empty. But this is not a coherent space that can be easily reused. Usually this is not a problem for btrfs and will be cleaned up automatically over time. However, if space is scarce (> 80% full), it is advisable to merge free areas together. This can be done by using balance with a filter.
+As you use your volume, you will be creating some files, deleting some, modifying some. Then some parts of the chunks are empty. But this is not a coherent space that can be easily reused. Usually this is not a problem for btrfs and will be cleaned up automatically over time. However, if space is scarce (> 85% full), it is advisable to merge free areas together. This can be done by using balance with a filter.
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 When you changed RAID-levels (for example from RAID 0 to RAID 1) there is no automatic duplication of the chunks. Only when writing further, btrfs will respect the changed RAID-level. This may not be what you intended. To complete the conversion to another RAID-level you need to tell btrfs to rewrite chunks where needed. You do this with a manual balance:
 </div>
+<div lang="en" dir="ltr" class="mw-content-ltr">
+=== Metadata ===
+It is rarely recommended to include blocks with metadata in a balance. It is advantageous, in exceptional cases, if the following conditions are currently met:
+You can check with:
+{{RootCmd|command=sudo btrfs fi us /|grep 'Meta.*Size'}}
+{{ic|Metadata,RAID1: Size:9.00GiB, Used:6.58GiB (73.09%)}}
+* Several GB of metadata are present in your filesystem (''6.6 GB present, 9 GB used'')
+* This metadata is poorly distributed (''73%'')
+* Significantly more than one full GB could become free (9 GB - 6.6 GB ==> ''2.4 GB could become free'')
+The command is then:
+{{RootCmd|command=btrfs balance start -musage=95 /}}
+Btrfs had to move 9 GB of metadata to free up 1 GB !
+{{ic|Metadata,RAID1: Size:8.00GiB, Used:6.58GiB (82.20%)}}
+</div>
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 ==== Avoid to get out of space with btrfs! ====
-Don't be stingy on storage space when creating a btrfs volume. A btrfs volume should normally only be 80% full.  Then it is advisable to adjust the volume. In an emergency, 90% are okay too. But that is neither advantageous for the Btrfs volume nor for an SSD.
+Don't skimp on storage space when creating a Btrfs volume. A Btrfs volume should normally be less than 90% full. Then it's recommended to adjust the volume. In an emergency, 95% (plus at least 5 GB free) is fine. However, this isn't beneficial for neither the Btrfs volume nor an SSD.
 {{BoxWarning|Don't forget to include the snapshots in the bill|Manjaro is a rolling release distribution. There will be a lot of changes over time.}}
 {{BoxInfo|Tip: Check how close you are to "out of space".| Look at '''Device unallocated:''' (not at ''Free (estimated):'') [https://forum.manjaro.org/t/could-not-boot-due-to-brfs-no-space-condition-how-should-i-keep-using-btrfs/92922/7 1]
 {{RootCmd|command=btrfs filesystem usage /}}
 }}
+</div>
+<div lang="en" dir="ltr" class="mw-content-ltr">
 === Get out of jail ===
 This said, there is an '''easy way out''': Give btrfs more space ;-)
 * '''add a (unformatted) partition''' (for example a fast extern USB-Stick with 8GB) to the btrfs-volume with{{RootCmd|command=btrfs device add /dev/[sdz4] /}}
 {{BoxDanger|Do NOT remove this USB-Stick|From now on this partition belongs to your volume! '''Do not boot without it'''. If possible do not reboot at all in this stage! This USB-stick has to stay until '''btrfs device remove''' has '''completed'''.}}
-* look for old snapshots you don´t need, remove them '''now'''
+* look for old snapshots you don´t need, remove them '''now''' (starting with the oldest one)
 * '''or delete some files''' you do not need
-* Do this until your disk will be not more then 95% full
+* Do this until your disk will be not more then 95% full (plus 5 GB free space)
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 {{BoxSuccess|Tip: Want to watch the volume clean up ?|{{UserCmd|command=pamac install procps-ng}}}}
 {{BoxSuccess||After that inside a terminal: {{RootCmd|command=watch -n 60 btrfs filesystem usage -h / }}}}
-* If neccesary '''balance''' your volume with a filter(90%) This '''will''' take some more time !{{RootCmd|command=btrfs balance start -dusage=95 /}}
+* If neccesary '''balance''' your volume with a filter(90-95 %) This '''will''' take some more time !{{RootCmd|command=btrfs balance start -dusage=95 /}}
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