求助..谁知道在linux下怎么挂上3tb的外设.

foobar

原帖由 nntp 于 2005-12-10 21:58 发表
n多人上来就用默认的ext3, ext3性能很糟糕，而且日志只有meta data才做，data区没有日志机制保护的，不像ReiserFS, JFS, XFS那样

ext3是可以保护data的一致性的，事实上用户可以选择三种不同的日志模式。我听说倒是JFS等系统不支持data journaling。

以下摘自：linux/Documentation/filesystems/ext3.txt

Data Mode
---------
There's 3 different data modes:

* writeback mode
In data=writeback mode, ext3 does not journal data at all.  This mode
provides a similar level of journaling as XFS, JFS, and ReiserFS in its
default mode - metadata journaling.  A crash+recovery can cause
incorrect data to appear in files which were written shortly before the
crash.  This mode will typically provide the best ext3 performance.

* ordered mode
In data=ordered mode, ext3 only officially journals metadata, but it
logically groups metadata and data blocks into a single unit called a
transaction.  When it's time to write the new metadata out to disk, the
associated data blocks are written first.  In general, this mode
perform slightly slower than writeback but significantly faster than
journal mode.

* journal mode
data=journal mode provides full data and metadata journaling.  All new
data is written to the journal first, and then to its final location.
In the event of a crash, the journal can be replayed, bringing both
data and metadata into a consistent state.  This mode is the slowest
except when data needs to be read from and written to disk at the same
time where it outperform all others mode.


BTW, 请问有什么数据支持"ext3性能很糟糕"这样的说法？

[ 本帖最后由 foobar 于 2006-1-22 02:28 编辑 ]

foobar

原帖由 nntp 于 2006-1-22 21:13 发表
道听途说，不如实际来做。opensource社区也有牛皮烘烘的东西.

ext3=烂.

BTW, 请问有什么"实际"数据支持"ext3=烂"这样的说法？牛皮烘烘，不如给点实际东西。

foobar

原帖由 wolfop 于 2006-1-23 14:43 发表

谁在生产系统中用data 日志的？真晕，自己试试性能如何吧，那么怕丢的化，还不如对数据区分类型，需要保护的用rdbms。而且大家都是日志meta data的情况，ext3的性能也比jfs xfs差距很大。rhas3忘记u几之前的ext3还有严重BUG会让内核panic。
此外ext3在调整fs大小的时候必须umount，呵呵。

只是说ext3可以支持data journaling (以回应bz的"ext3的data区没有日志机制保护的"的说法)，至于是不是适用于生产系统，那是另外的问题了。

“此外ext3在调整fs大小的时候必须umount”，这是老皇历了(RHEL4之前)。请先看看RHEL4中的ext2online命令。

至于ext3/jfs/xfs的性能比较，那恐怕是需要具体数据来说话了。至于那个严重BUG，如果方便的话最好也提供一些具体信息。实事求是嘛。