Merge pull request #1402 from trapexit/docs

Doc and mover script updates

Author: trapexit

mkdocs/docs/faq/reliability_and_scalability.md

@@ -26,6 +26,16 @@ Users have pooled everything from USB thumb drives to enterprise NVME
 SSDs to remote filesystems and rclone mounts.
 
 The cost of many calls can be `O(n)` meaning adding more branches to
-the pool will increase the cost of certain functions but there are a
-number of caches and strategies in place to limit overhead where
-possible.
+the pool will increase the cost of certain functions, such as reading
+directories or finding files to open, but there are a number of caches
+and strategies in place to limit overhead where possible.
+
+
+## Are there any limits?
+
+There is no maximum capacity beyond what is imposed by the operating
+system itself. Any limit is practical rather than technical. As
+explained in the question about scale mergerfs is mostly limited by
+the tolerated cost of aggregating branches and the cost associated
+with interacting with them. If you pool slow network filesystem then
+that will naturally impact performance more than low latency SSDs.

mkdocs/docs/media_and_publicity.md

@@ -20,12 +20,16 @@
 - 2020-08-20 - [Setting up Rclone, Mergerfs and Crontab for automated cloud storage](https://bytesized-hosting.com/pages/setting-up-rclone-mergerfs-and-crontab-for-automated-cloud-storage)
 - 2020-11-22 - [Introducing… MergerFS – My FREE UNRAID alternative](https://supertechfreaks.com/introducing-mergerfs-free-unraid-alternative/)
 - 2020-12-30 - [Perfect Media Server](https://perfectmediaserver.com) (a new site with docs fully fleshing out the 'Perfect Media Server' blog series)
+- 2021-07-24 - [Building the Ultimate Linux Home Server - Part 1: Intro, MergerFS, and SnapRAID](https://blog.karaolidis.com/ultimate-home-server-part-1/)
 - 2021-10-31 - [Better Home Storage: MergerFS + SnapRAID on OpenMediaVault](https://blog.sakuragawa.moe/better-home-storage-mergerfs-snapraid-on-openmediavault/)
 - 2021-11-28 - [Linux Magazine: Come Together - Merging file systems for a simple NAS with MergerFS](https://www.linux-magazine.com/Issues/2022/254/MergerFS)
 - 2022-06-04 - [MergerFS + SnapRaid Study](https://crashlaker.github.io/2022/06/04/mergerfs_+_snapraid_study.html)
 - 2022-12-31 - [Merge Storages in CasaOS: A secret beta feature you know now](https://blog.casaos.io/blog/13.html)
 - 2023-02-03 - [(MergerFS + SnapRAID) is the new RAID 5](https://thenomadcode.tech/mergerfs-snapraid-is-the-new-raid-5)
 - 2024-02-07 - [Designing & Deploying MANS - A Hybrid NAS Approach with SnapRAID, MergerFS, and OpenZFS](https://blog.muffn.io/posts/part-3-mini-100tb-nas)
+- 2024-03-11 - [Using MergerFS to combine multiple hard drives into one unified media storage](https://fullmetalbrackets.com/blog/two-drives-mergerfs/)
+- 2024-12-20 - [Pooling multiple drives on my Raspberry Pi with mergerfs](https://sebi.io/posts/2024-12-20-pooling-multiple-drives-with-mergerfs/)
+
 
 ## Videos
 
@@ -56,16 +60,21 @@
 - 2023-06-26 - [How to install and setup MergerFS](https://www.youtube.com/watch?v=n7piuhTXeG4)
 - 2023-07-31 - [How to recover a dead drive using Snapraid](https://www.youtube.com/watch?v=fmuiRLPcuJE)
 - 2024-01-05 - [OpenMediaVault MergerFS Tutorial (Portuguese)](https://www.youtube.com/watch?v=V6Yw86dRUPQ)
+- 2024-02-19 - [Setup and Install MergerFS and SnapRAID (Part 1)](https://noted.lol/mergerfs-and-snapraid-setup-1/)
+- 2024-02-22 - [Setup and Install MergerFS and SnapRAID (Part 2)](https://noted.lol/mergerfs-and-snapraid-setup-part-2/)
 - 2024-11-15 - [Meu servidor NAS - Parte 18: Recuperando um HD, recuperando o MergerFS e os próximos passos do NAS!](https://www.youtube.com/watch?v=5fy98kPzE3s)
 
+
 ## Podcasts
 
 - 2019-11-04 - [Jupiter Extras: A Chat with mergerfs Developer Antonio Musumeci | Jupiter Extras 28](https://www.youtube.com/watch?v=VmJUAyyhSPk)
 - 2019-11-07 - [Jupiter Broadcasting: ZFS Isn’t the Only Option | Self-Hosted 5](https://www.youtube.com/watch?v=JEW7UuKhMJ8)
 - 2023-10-08 - [Self Hosted Episode 105 - Sleeper Storage Technology](https://selfhosted.show/105)
 
+
 ## Social Media
 
 - [Reddit](https://www.reddit.com/search/?q=mergerfs&sort=new)
-- [Twitter](https://twitter.com/search?q=mergerfs&src=spelling_expansion_revert_click&f=live)
+- [X](https://x.com/search?q=mergerfs&src=spelling_expansion_revert_click&f=live)
 - [YouTube](https://www.youtube.com/results?search_query=mergerfs&sp=CAI%253D)
+- [ServeTheHome Forum](https://forums.servethehome.com/index.php?search/3105813/&q=mergerfs&o=date)

mkdocs/docs/related_projects.md

@@ -21,16 +21,33 @@
 
 ## Software and services commonly used with mergerfs
 
-* [snapraid](https://www.snapraid.it/)
-* [rclone](https://rclone.org/)
-  * rclone's [union](https://rclone.org/union/) feature is based on
-    mergerfs policies
-* [ZFS](https://openzfs.org/): Common to use ZFS w/ mergerfs
+* [snapraid](https://www.snapraid.it/): a backup program designed for
+  disk arrays, storing parity information for data recovery in the
+  event of up to six disk failures.
+* [rclone](https://rclone.org/): a command-line program to manage
+  files on cloud storage. It is a feature-rich alternative to cloud
+  vendors' web storage interfaces. rclone's
+  [union](https://rclone.org/union/) feature is based on mergerfs
+  policies.
+* [ZFS](https://openzfs.org/): Common to use ZFS w/ mergerfs. ZFS for
+  important data and mergerfs pool for replacable media.
 * [UnRAID](https://unraid.net): While UnRAID has its own union
   filesystem it isn't uncommon to see UnRAID users leverage mergerfs
-  given the differences in the technologies.
-* For a time there were a number of Chia miners recommending mergerfs
-* [cloudboxes.io](https://cloudboxes.io/wiki/how-to/apps/set-up-mergerfs-using-ssh)
+  given the differences in the technologies. There is a [plugin
+  available by
+  Rysz](https://forums.unraid.net/topic/144999-plugin-mergerfs-for-unraid-support-topic/)
+  to ease installation and setup.
+* [TrueNAS](https://www.truenas.com): Some users are requesting
+  mergerfs be [made part
+  of](https://forums.truenas.com/t/add-unionfs-or-mergerfs-and-rdam-enhancement-then-beat-all-other-nas-systems/23218)
+  TrueNAS.
+* For a time there were a number of Chia miners recommending mergerfs.
+* [cloudboxes.io](https://cloudboxes.io): VPS provider. Includes
+  details [on their
+  wiki](https://cloudboxes.io/wiki/how-to/apps/set-up-mergerfs-using-ssh):
+  on how to setup mergerfs.
+* [QNAP](https://www.myqnap.org/product/mergerfs-apache83/): Someone
+  has create builds of mergerfs for different QNAP devices.
 
 
 ## Distributions including mergerfs

mkdocs/docs/usage_patterns.md

@@ -29,60 +29,91 @@ across filesystems (see the mergerfs.dup tool) and setting
 `func.open=rand`, using `symlinkify`, or using dm-cache or a similar
 technology to add tiered cache to the underlying device itself.
 
-With #2 one could use dm-cache as well but there is another solution
-which requires only mergerfs and a cronjob.
-
-1.  Create 2 mergerfs pools. One which includes just the slow branches
-    and one which has both the fast branches (SSD,NVME,etc.) and slow
-    branches. The 'base' pool and the 'cache' pool.
-2.  The 'cache' pool should have the cache branches listed first in
-    the branch list.
-3.  The best `create` policies to use for the 'cache' pool would
-    probably be `ff`, `epff`, `lfs`, `msplfs`, or `eplfs`. The latter
-    three under the assumption that the cache filesystem(s) are far
-    smaller than the backing filesystems. If using path preserving
-    policies remember that you'll need to manually create the core
-    directories of those paths you wish to be cached. Be sure the
-    permissions are in sync. Use `mergerfs.fsck` to check / correct
-    them. You could also set the slow filesystems mode to `NC` though
-    that'd mean if the cache filesystems fill you'd get "out of space"
-    errors.
-4.  Enable `moveonenospc` and set `minfreespace` appropriately. To
-    make sure there is enough room on the "slow" pool you might want
-    to set `minfreespace` to at least as large as the size of the
-    largest cache filesystem if not larger. This way in the worst case
-    the whole of the cache filesystem(s) can be moved to the other
-    drives.
-5.  Set your programs to use the 'cache' pool.
-6.  Save one of the below scripts or create you're own. The script's
-    responsibility is to move files from the cache filesystems (not
-    pool) to the 'base' pool.
-7.  Use `cron` (as root) to schedule the command at whatever frequency
-    is appropriate for your workflow.
+With #2 one could use a block cache solution as available via LVM and
+dm-cache but there is another solution which requires only mergerfs, a
+script to move files around, and a cron job to run said script.
+
+* Create two mergerfs pools. One which includes just the **slow**
+  branches and one which has both the **fast** branches
+  (SSD,NVME,etc.) and **slow** branches. The **base** pool and the
+  **cache** pool.
+* The **cache** pool should have the cache branches listed first in
+  the branch list in order to to make it easier to prioritize them.
+* The best `create` policies to use for the **cache** pool would
+  probably be `ff`, `lus`, or `lfs`. The latter two under the
+  assumption that the cache filesystem(s) are far smaller than the
+  backing filesystems.
+* You can also set the **slow** filesystems mode to `NC` which would
+  give you the ability to use other `create` policies though that'd
+  mean if the cache filesystems fill you'd get "out of space"
+  errors. This however may be good as it would indicate the script
+  moving files around is not configured properly.
+* Set your programs to use the **cache** pool.
+* Configure the **base** pool with the `create` policy you would like
+  to lay out files as you like.
+* Save one of the below scripts or create your own. The script's
+  responsibility is to move files from the **cache** branches (not
+  pool) to the **base** pool.
+* Use `cron` (as root) to schedule the command at whatever frequency
+  is appropriate for your workflow.
 
 
 ### time based expiring
 
-Move files from cache to base pool based only on the last time the
-file was accessed. Replace `-atime` with `-amin` if you want minutes
-rather than days. May want to use the `fadvise` / `--drop-cache`
-version of rsync or run rsync with the tool
-[nocache](https://github.com/Feh/nocache).
+Move files from cache filesystem to base pool which have an access
+time older than the supplied number of days. Replace `-atime` with
+`-amin` in the script if you want minutes rather than days.
 
 **NOTE:** The arguments to these scripts include the cache
 **filesystem** itself. Not the pool with the cache filesystem. You
 could have data loss if the source is the cache pool.
 
 [mergerfs.time-based-mover](https://github.com/trapexit/mergerfs/blob/latest-release/tools/mergerfs.time-based-mover?raw=1)
 
+Download:
+```
+curl -o /usr/local/bin/mergerfs.time-based-mover https://raw.githubusercontent.com/trapexit/mergerfs/refs/heads/latest-release/tools/mergerfs.time-based-mover
+```
+
+crontab entry:
+```
+# m h  dom mon dow   command
+0 * * * * /usr/local/bin/mergerfs.time-based-mover /mnt/ssd/cache00 /mnt/base-pool 1
+```
+
+If you have more than one cache filesystem then simply add a cron
+entry for each.
+
+If you want to only move files from a subdirectory then use the
+subdirectories. `/mnt/ssd/cache00/foo` and `/mnt/base-pool/foo`
+respectively.
+
 
 ### percentage full expiring
 
-Move the oldest file from the cache to the backing pool. Continue till
-below percentage threshold.
+While the cache filesystem's percentage full is above the provided
+value move the oldest file from the cache filesystem to the base pool.
 
 **NOTE:** The arguments to these scripts include the cache
 **filesystem** itself. Not the pool with the cache filesystem. You
 could have data loss if the source is the cache pool.
 
 [mergerfs.percent-full-mover](https://github.com/trapexit/mergerfs/blob/latest-release/tools/mergerfs.percent-full-mover?raw=1)
+
+Download:
+```
+curl -o /usr/local/bin/mergerfs.percent-full-mover https://raw.githubusercontent.com/trapexit/mergerfs/refs/heads/latest-release/tools/mergerfs.percent-full-mover
+```
+
+crontab entry:
+```
+# m h  dom mon dow   command
+0 * * * * /usr/local/bin/mergerfs.percent-full-mover /mnt/ssd/cache00 /mnt/base-pool 80
+```
+
+If you have more than one cache filesystem then simply add a cron
+entry for each.
+
+If you want to only move files from a subdirectory then use the
+subdirectories. `/mnt/ssd/cache00/foo` and `/mnt/base-pool/foo`
+respectively.

tools/mergerfs.percent-full-mover

@@ -1,21 +1,37 @@
 #!/usr/bin/env sh
 
 if [ $# != 3 ]; then
-  echo "usage: $0 <cache-fs> <backing-pool> <percentage>"
-  exit 1
+    echo "usage: $0 <cache-fs> <base-pool> <percentage>"
+    exit 1
 fi
 
-CACHE="${1}"
-BACKING="${2}"
+CACHEFS="${1}"
+BASEPOOL="${2}"
 PERCENTAGE=${3}
 
 set -o errexit
-while [ $(df --output=pcent "${CACHE}" | grep -v Use | cut -d'%' -f1) -gt ${PERCENTAGE} ]
+while [ $(df "${CACHE}" | tail -n1 | awk '{print $5}' | cut -d'%' -f1) -gt ${PERCENTAGE} ]
 do
+    # Find the file with the oldest access time
     FILE=$(find "${CACHE}" -type f -printf '%A@ %P\n' | \
-                  sort | \
-                  head -n 1 | \
-                  cut -d' ' -f2-)
-    test -n "${FILE}"
-    rsync -axqHAXWESR --preallocate --relative --remove-source-files "${CACHE}/./${FILE}" "${BACKING}/"
+               sort | \
+               head -n 1 | \
+               cut -d' ' -f2-)
+    # If no file found, exit
+    test -n "${FILE}" || exit 0
+    # Move file
+    rsync \
+        --archive \
+        --acls \
+        --xattrs \
+        --atimes \
+        --hard-links \
+        --one-file-system \
+        --quiet \
+        --preallocate \
+        --remove-source-files \
+        --relative \
+        --log-file=/tmp/mergerfs-cache-rsync.log \
+        "${CACHE}/./${FILE}" \
+        "${BACKING}/"
 done

tools/mergerfs.time-based-mover

@@ -1,13 +1,26 @@
 #!/usr/bin/env sh
 
 if [ $# != 3 ]; then
-  echo "usage: $0 <cache-fs> <backing-pool> <days-old>"
-  exit 1
+    echo "usage: $0 <cache-fs> <base-pool> <days-old>"
+    exit 1
 fi
 
-CACHE="${1}"
-BACKING="${2}"
-N=${3}
+CACHEFS="${1}"
+BASEPOOL="${2}"
+DAYS_OLD=${3}
 
-find "${CACHE}" -type f -atime +${N} -printf '%P\n' | \
-  rsync --files-from=- -axqHAXWES --preallocate --remove-source-files "${CACHE}/" "${BACKING}/"
+find "${CACHEFS}" -type f -atime +${DAYS_OLD} -printf '%P\n' | \
+    rsync \
+        --files-from=- \
+        --archive \
+        --acls \
+        --xattrs \
+        --atimes \
+        --hard-links \
+        --one-file-system \
+        --quiet \
+        --preallocate \
+        --remove-source-files \
+        --log-file=/tmp/mergerfs-cache-rsync.log \
+        "${CACHEFS}/" \
+        "${BASEPOOL}/"