fc fs筆記
https://openzfs.topicbox.com/groups/developer/T950b02acdf392290/odirect-semantics-in-zfs O_DIRECT semantics notes in zfs
https://github.com/openzfs/zfs/pull/10018 PR for DirectIO in openzfs
GitHub
Direct IO Support by bwatkinson · Pull Request #10018 · openzfs/zfs
Adding O_DIRECT support to ZFS.
Motivation and Context
By adding Direct IO support to ZFS, the ARC can be bypassed when issuing reads/writes.
There are certain cases where caching data in the ARC c...
Motivation and Context
By adding Direct IO support to ZFS, the ARC can be bypassed when issuing reads/writes.
There are certain cases where caching data in the ARC c...
https://github.com/pjd/openzfs/commit/184c9e78733381c7cc4f0b18e9d6819a6f3c1c66 BRT based reflink implementation (copy_file_range) for openzfs , about to PR hopefully
GitHub
Implementation of block cloning for ZFS. · pjd/openzfs@184c9e7
Block Cloning allows to manually clone a file (or a subset of its
blocks) into another (or the same) file by just creating additional
references to the data blocks without copying the data itself.
...
blocks) into another (or the same) file by just creating additional
references to the data blocks without copying the data itself.
...
https://github.com/openzfs/zfs/pull/13392 openzfs 基於 BRT 的 block cloning (reflink) 終於 merge 了
GitHub
Block Cloning by pjd · Pull Request #13392 · openzfs/zfs
Motivation and Context
Block Cloning allows to clone a file (or a subset of its blocks) into another (or the same) file by just creating additional references to the data blocks without copying the...
Block Cloning allows to clone a file (or a subset of its blocks) into another (or the same) file by just creating additional references to the data blocks without copying the...
fc fs筆記
https://blog.stuffedcow.net/2019/09/hard-disk-geometry-microbenchmarking/
（自己的筆記經常找不到鏈接於是記錄一下） 通過 microbenchmarking 測量 LBA 間跳轉消耗的 seek time 來測量現代 hdd 上 LBA 的具體物理扇區映射關係。可以看出近現代硬盤上扇區佈局已經發展到傳統的柱面之類的概念沒有什麼實際意義了
Forwarded from 糊锅
A kernel without buffer heads
https://lwn.net/SubscriberLink/930173/c288defca11561e8/
https://lwn.net/SubscriberLink/930173/c288defca11561e8/
lwn.net
A kernel without buffer heads
No data structures found in the Linux kernel — at least, in any version
that escaped from Linus Torvalds's development machine — are older than the
buffer head. Like many other legacies from the early days of Linux, buffer
heads have been targeted for removal…
that escaped from Linus Torvalds's development machine — are older than the
buffer head. Like many other legacies from the early days of Linux, buffer
heads have been targeted for removal…
fc fs筆記
A kernel without buffer heads https://lwn.net/SubscriberLink/930173/c288defca11561e8/
關了 buffer heads 支持會得到一個有 xfs btrfs 沒有 ext4 f2fs jfs ntfs3 fat 和 dm 的內核
https://youtu.be/NtkKHhXf3V4 linux nvme and block layer
YouTube
Linux NVMe and block layer status update (SDC 2019)
This talks explains the exciting new features in the Linux NVMe driver and software target in the last two years, as well as the
relevant block layer changes to support these features.
Presented by Christoph Hellwig, Kernel Hacker
Learn More:
SDC Website:…
relevant block layer changes to support these features.
Presented by Christoph Hellwig, Kernel Hacker
Learn More:
SDC Website:…
https://www.vidarholen.net/contents/blog/?p=479 tl;dr: dd works for reading and writing disks, but it has no "low level I/O" capabilities that make it more suited for this than any other shell utility. Like cat you should use it where it makes sense, e.g. to take advantage of its wide array of options, rather than try to ensure that all disk related commands begin and end with dd out of fear and superstition.
https://lore.kernel.org/linux-btrfs/20231217165359.604246-1-hch@lst.de/ host-aware SMR hdd 從 SCSI / ATA 標準中刪掉了(NVMe 標準中沒有加過)，今後就只會有 host-managed 和 device-managed SMR 了。 Linux 內核會把現存少量的 host-aware SMR 設備當作 device-managed SMR （OS 看來是普通的 HDD ）用
https://www.evanjones.ca/durability-nvme.html
關於 NVMe 設備上寫入的語義的一些解讀，引用到了 NVMe 標準，對不想細讀標準是一個不錯的總結
關於 NVMe 設備上寫入的語義的一些解讀，引用到了 NVMe 標準，對不想細讀標準是一個不錯的總結
fc fs筆記
rst-linux-paper.pdf https://www.intel.com/content/dam/www/public/us/en/documents/white-papers/rst-linux-paper.pdf
Intel RST 在 linux 上用 mdadm 的文檔
Forwarded from Linux - Reddit
Understanding Unix filesystem timestamps
https://unixdigest.com/articles/understanding-unix-filesystem-timestamps.html
https://redd.it/1j8jhvt
@r_linux
https://unixdigest.com/articles/understanding-unix-filesystem-timestamps.html
https://redd.it/1j8jhvt
@r_linux
https://despairlabs.com/blog/posts/2025-03-13-fsync-after-open-is-an-elaborate-no-op/ fsync 具體行為有多模糊
despair labs
fsync() after open() is an elaborate no-op
I have spent the last couple of years of my life trying to make sense of fsync() and bringing OpenZFS up to code. I’ve read a lot of horror stories about this apparently-simple syscall in that time, usually written by people who tried very hard to get it…
fc fs筆記
https://despairlabs.com/blog/posts/2025-03-13-fsync-after-open-is-an-elaborate-no-op/ fsync 具體行為有多模糊
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