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星期三, 四月 22, 2009
EXT4很好很強大

雖然EXT4檔案系統之前有這個問題,但是新的Ubuntu 9.04發行版已經做了patch,以及Linux核心本身的下一版會予以解決:

Delayed allocation and potential data loss

The delayed allocation poses some additional risk of data loss in cases where the system crashes before all data has been written to the disk.

The typical scenario is a program that replaces the content of a file, without forcing a write to the disk with fsync. If the system crashes shortly afterwards, it is really undefined what is supposed to happen. However, users have come to expect that the disk holds either the old version or the new version of the file, a behaviour that ext3 would usually yield. Whereas the ext4 code in kernel 2.6.28 will often have truncated the file to zero length before the crash, but not yet written the new version, so that the contents of the file is lost.

Many people find such system behavior unacceptable. A significant issue is that fixing the bug, by using fsync more often, could lead to severe performance penalties on ext3 file-systems mounted with the data=ordered flag (the default on most Linux distributions). Given that both file-systems will be in use for some time, this complicates matters enormously for end-user application developers. In response, Theodore Ts'o has written some patches for ext4 that cause it to limit its delayed allocation in these common cases. For a small cost in performance, this will significantly increase the chance that a version of the file survives the crash.

The new patches are expected to become part of the mainline kernel 2.6.30. Various distributions may choose to backport them to 2.6.28 or 2.6.29, for instance Ubuntu made them part of the 2.6.28 kernel in version 9.04 -- Jaunty Jackalope.

我自己使用的結果,EXT4是真的很好很強大啊。

舉個簡單例子,原本桌機用的是XFS,在桌面環境中,執行套件管理程式總要等很久的時間,但改用EXT4後,速度快了1倍,是很明顯可感受到的使用者經驗。以傳統硬碟來看bootchart測試grub開機選單到進入桌面,速度為18秒,而如果是用SSD,速度快到只要9.2秒。

還滿建議在個人電腦上使用EXT4檔案系統的。

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ivan 發表於 11:49 PM | 文章分類: 數位科技, software | 標籤列表:

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還是等EXT完全穩定了在升級。
anopos 發表於 9:59, 五月 5, 2009
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Amd barton 2500+ ,20g HD , ati 64mb 8x atp vga , 1g ram ,跑起來比 windows me , xp 快一點, 又不怕中毒,除了一點點毛病(當過一次)外,其他都幾乎無懈可擊.安裝又快又容易,大家一起來玩吧!
由 donder 發表於 22:51, 五月 8, 2009
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