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Dirty pages in /proc/meminfo

market_garden · 2015-11-04 16:16:46

A RedHat system has dirty pages in /proc/meminfo. Is it possible that there could be data loss if the system crashes? Is it possible to prevent this? Can we tell what would be lost exactly and is it possible to repair it?

04-11-2015 4:16pm

#1

market_garden

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Join Date: September 2008

Posts: 21

A RedHat system has dirty pages in /proc/meminfo.
Is it possible that there could be data loss if the system crashes? Is it possible to prevent this?
Can we tell what would be lost exactly and is it possible to repair it?

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Comments

#2 04-11-2015 4:32pm

jimgoose

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Holding dirty pages in core is always going to be a risky business. In a kernel panic, it's gone and there isn't much you can do about it. How much dirty stuff is showing? I suggest tuning /proc/sys/vm/dirty_ratio, /proc/sys/vm/dirty_expire_centisecs and /proc/sys/vm/dirty_writeback_centisecs to minimise the amount held, and thus the potential exposure.

I don't think it's possible to inspect the Unix/Linux filesystem caches from userland. The best you can do is, if you're wondering about a particular file, mmap() it and find out if the pages are already resident using mincore().

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