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phuslu 2013-08-20 11:30:06 +08:00 2
一般用 xfs 并且 mount noatime
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oldcai OP @phuslu
http://xfs.org/index.php/XFS_FAQ 说没必要mount noatime。读的时候不记录atime是可以避免读的时候的写操作,但是写不一定是马上写到硬盘上的,应该对io的影响方面,关系不大吧。 不过如果只用作mongodb的文件系统,也确实没必要记录atime 引用: The default atime behaviour is relatime, which has almost no overhead compared to noatime but still maintains sane atime values. All Linux filesystems use this as the default now (since around 2.6.30), but XFS has used relatime-like behaviour since 2006, so no-one should really need to ever use noatime on XFS for performance reasons. |
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lixm 2013-08-20 16:18:38 +08:00 1
楼主对写时复制的理解有误吧, 写时复制是用来做快照的
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pubby 2013-08-20 16:28:35 +08:00 1
不一定是复制整个文件,ZFS那么先进的文件系统没那么脑残。
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oldcai OP @pubby
性能影响是有的,但是程度还未知,所以还是试试 @phuslu 推荐的xfs先,看了下,支持超大文件,支持快照,支持碎片整理,还是不错的。 https://groups.google.com/forum/#!topic/mongodb-user/HWLECIxg9ug That said, there may be ways to disable COW on ZFS since most databases expect in-place updates. However I am not enough of an expert in ZFS to know how to do this. You may already have it set up that way for MySQL. |
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oldcai OP 少复制了一段。。
We've heard reports of slowdowns due to it's copy-on-write behavior leading to objects being out-of-order on disk and needing more seeking. To some extent, MongoDB's performance (both read and write) relies on in-place updating. |