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@ -1294,10 +1294,11 @@ https://en.wikipedia.org/wiki/Page_cache |
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unchanged since previous open. |
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* cache.files=libfuse: follow traditional libfuse `direct_io`, |
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`kernel_cache`, and `auto_cache` arguments. |
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* cache.files=per-process: Enable page caching (equivalent to `cache.files=partial`) |
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only for processes whose 'comm' name matches one of the values defined in |
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`cache.files.process-names`. If the name does not match the file open |
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is equivalent to `cache.files=off`. |
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* cache.files=per-process: Enable page caching (equivalent to |
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`cache.files=partial`) only for processes whose 'comm' name matches |
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one of the values defined in `cache.files.process-names`. If the |
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name does not match the file open is equivalent to |
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`cache.files=off`. |
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FUSE, which mergerfs uses, offers a number of page caching modes. mergerfs tries to simplify their use via the `cache.files` |
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option. It can and should replace usage of `direct_io`, |
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@ -1428,7 +1429,7 @@ placing of usually smaller, faster storage as a transparent cache to |
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larger, slower storage. NVMe, SSD, Optane in front of traditional HDDs |
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for instance. |
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MergerFS does not natively support any sort of tiered caching. Most |
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mergerfs does not natively support any sort of tiered caching. Most |
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users have no use for such a feature and its inclusion would |
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complicate the code. However, there are a few situations where a cache |
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filesystem could help with a typical mergerfs setup. |
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@ -1901,18 +1902,51 @@ of which are fixed in stable releases. |
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#### Can mergerfs be used with filesystems which already have data / are in use? |
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Yes. MergerFS is a proxy and does **NOT** interfere with the normal |
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form or function of the filesystems / mounts / paths it manages. |
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Yes. mergerfs is really just a proxy and does **NOT** interfere with |
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the normal form or function of the filesystems / mounts / paths it |
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manages. It is just another userland application that is acting as a |
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man-in-the-middle. It can't do anything that any other random piece of |
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software can't do. |
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MergerFS is **not** a traditional filesystem. MergerFS is **not** |
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RAID. It does **not** manipulate the data that passes through it. It |
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does **not** shard data across filesystems. It merely shards some |
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**behavior** and aggregates others. |
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mergerfs is **not** a traditional filesystem that takes control over |
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the underlying block device. mergerfs is **not** RAID. It does **not** |
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manipulate the data that passes through it. It does **not** shard data |
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across filesystems. It merely shards some **behavior** and aggregates |
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others. |
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#### Can drives/filesystems be removed from the pool at will? |
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Yes. See previous question's answer. |
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#### Can mergerfs be removed without affecting the data? |
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See the previous question's answer. |
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Yes. See the previous question's answer. |
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#### Can drives/filesystems be moved to another pool? |
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Yes. See the previous question's answer. |
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#### How do I migrate data into or out of the pool when adding/removing drives/filesystems? |
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You don't need to. See the previous question's answer. |
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#### How do I remove a drive/filesystem but keep the data in the pool? |
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Nothing special needs to be done. Remove the branch from mergerfs' |
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config and copy (rsync) the data from the removed filesystem into the |
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pool. Effectively the same as if it were you transfering data from one |
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filesystem to another. |
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If you wish to continue using the pool while performing the transfer |
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simply create another, temporary pool without the filesystem in |
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question and then copy the data. It would probably be a good idea to |
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set the branch to `RO` prior to doing this to ensure no new content is |
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written to the filesystem while performing the copy. |
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#### What policies should I use? |
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@ -2132,7 +2166,7 @@ removed to simplify the codebase. |
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#### Why use mergerfs over mhddfs? |
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mhddfs is no longer maintained and has some known stability and |
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security issues (see below). MergerFS provides a superset of mhddfs' |
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security issues (see below). mergerfs provides a superset of mhddfs' |
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features and should offer the same or maybe better performance. |
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Below is an example of mhddfs and mergerfs setup to work similarly. |
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@ -2181,7 +2215,7 @@ without the single point of failure. |
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#### Why use mergerfs over ZFS? |
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MergerFS is not intended to be a replacement for ZFS. MergerFS is |
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mergerfs is not intended to be a replacement for ZFS. mergerfs is |
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intended to provide flexible pooling of arbitrary filesystems (local |
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or remote), of arbitrary sizes, and arbitrary filesystems. For `write |
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once, read many` usecases such as bulk media storage. Where data |
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trapexit
9 months ago
GitHub