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author | David Sterba <dsterba@suse.com> | 2024-03-25 23:29:01 +0100 |
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committer | David Sterba <dsterba@suse.com> | 2024-03-25 23:33:25 +0100 |
commit | 5cfa61d6e83c601bbdcc98bba84cf93c6df91b5e (patch) | |
tree | 0122453d2b86253d26159f1b99851a495653acb3 | |
parent | 2c99d8078f005a2354341d167a93fa065a8bd70e (diff) | |
download | btrfs-progs-5cfa61d6e83c601bbdcc98bba84cf93c6df91b5e.tar.gz |
btrfs-progs: docs: update memory related problems
Inspired by https://www.reddit.com/r/btrfs/comments/1bkdewb/btrfs_errors_in_dmesg/ .
[ci skip]
Signed-off-by: David Sterba <dsterba@suse.com>
-rw-r--r-- | Documentation/ch-hardware-considerations.rst | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/Documentation/ch-hardware-considerations.rst b/Documentation/ch-hardware-considerations.rst index 42e8ca68..50a9b987 100644 --- a/Documentation/ch-hardware-considerations.rst +++ b/Documentation/ch-hardware-considerations.rst @@ -118,9 +118,21 @@ have been demonstrated (*rowhammer*) achieving specific bits to be flipped. While these were targeted, this shows that a series of reads or writes can affect unrelated parts of memory. +Block group profiles with redundancy (like RAID1) will not protect against +memory errors as the blocks are first stored in memory before they are written +to the devices from the same source. + +A filesystem mounted read-only will not affect the underlying block device in +almost 100% (with highly unlikely exceptions). The exception is a tree-log that +needs to be replayed during mount (and before the read-only mount takes place), +working memory is needed for that and that can be affected by bit flips. +There's a theoretical case where bit flip changes the filesystem status from +read-only to read-write. + Further reading: * https://en.wikipedia.org/wiki/Row_hammer +* memory overclocking, XMP, potential risks What to do: @@ -129,6 +141,9 @@ What to do: * memory errors may appear as filesystem going read-only due to "pre write" check, that verify meta data before they get written but fail some basic consistency checks +* newly built systems should be tested before being put to production use, + ideally start a IO/CPU load that will be run on such system later; namely + systems that will utilize overclocking or special performance features Direct memory access (DMA) ^^^^^^^^^^^^^^^^^^^^^^^^^^ |