APFS 真係得啖笑

fatdog

最重要嘅 data integrity 竟然係唔包 user data ...
只係 check metadata ...

即係比 zfs 落後 ...

evec

唔包？
https://developer.apple.com/libr ... DontLinkElementID_1
What has Apple done to ensure the reliability of my data?

Apple products are designed to prevent data corruption and protect against data loss.

To protect data from hardware errors, all Flash/SSD and hard disk drives used in Apple products use Error Correcting Code (ECC). ECC checks for transmission errors, and when necessary, corrects on the fly. Apple File System uses a unique copy-on-write scheme to protect against data loss that can occur during a crash or loss of power. And to further ensure data integrity, Apple File System uses the Fletcher's checksum algorithm for metadata operations.

Does Apple File System use journaling?

Apple File System uses copy-on-write to avoid in-place changes to file data, which ensures that file system updates are crash protected without the write-twice overhead of journaling.

556556bt

最重要嘅 data integrity 竟然係唔包 user data ...
只係 check metadata ...

即係比 zfs 落後 ... ...
fatdog 發表於 2017-6-6 04:56

    應該唔會. FS 係全隻碟架啦.. 點會分唔同folder. 不過APFS 初期出. 會否同現有app 有conflict 就要睇過先知.

fatdog

唔包？

What has Apple done to ensure the reliability of my data?

Apple products are designed to pr ...
evec 發表於 2017-6-6 09:36

ecc & cow 唔係果樣野黎

https://en.wikipedia.org/wiki/Apple_File_System#Data_integrity

Data integrity
Apple File System uses checksums to ensure data integrity for metadata, but not user data.

http://dtrace.org/blogs/ahl/2016/06/19/apfs-part5/
no checksums for user data

556556bt

ecc & cow 唔係果樣野黎





no checksums for user data
fatdog 發表於 2017-6-6 13:56

    呢個會唔會係apply for IOS only?

user data 呢個字係osx 咪即係所有你安入去都係user data 啦?

evec

ecc & cow 唔係果樣野黎





no checksums for user data
fatdog 發表於 2017-6-6 13:56

1. 對User Data （這是指Metadata外的資料）無CheckSum 唔代表無 Data Integrity。
2.額外 CheckSum 要求額外容量，額外硬件資源開銷，CheckSum太小都是沒用，太大也就特別浪費尤其SSD上的資源，而且SSD同HD其實內部都有做容錯，在Filesystem上額外做資料CheckSum其實除咗知資料錯其實作用不大（反正磁碟或SSD都會報錯），只對Metadata作Checksum 檢查在APFS應用上無問題，加上Apple講明有機制防止資料因OS層或斷電的損失，
單單指沒有對資料做CheckSum唔代表APFS是比ZFS落後。