On 29/08/11 07:00, green wrote:
Scott Ferguson wrote at 2011-08-28 10:19 -0500:On 29/08/11 00:03, green wrote:Scott Ferguson wrote at 2011-08-27 08:50 -0500:I don't imagine upgrading will make much difference - the controller distributes the writes evenly, for which reason I reserve 25% of space when installing (instead of the default 10%). NOTE: I could be wrong about that - I'm just guessing.Hmm, that reserves 25% for root use only, something that occurs above the filesystem level.Is that a specific area that's reserved - or just an amount of space kept free for root?mke2fs(8): "percentage of the filesystem blocks" I read that as just an amount of space reserved so that if a regular user fills up the filesystem, he is denied further writes while root processes can still write.
Which was roughly my interpretation - a certain amount of shuffle space is left which isn't used by user processes, but can at any given time be any areas of the filesystem.
If I get a chance I'll dig up the paper written earlier this year about SSD write controller, from foggy memory it was a local research effort - upset the forensics experts at the time, and goes into detail about how the controllers actually present the system.(which is completely different to how conventional physical drives do things).
Sorry, brain not working today, very late night battling cPanel limitations and SSL problems.
Currently I use ext3 which has (major) fragmentation problems when it runs short on space (90-95% of space) - especially when used for lots of frequent, small writes as it is.mke2fs(8) does mention using a reserved-blocks-percentage to reduce fragmentation. But it only limits user processes.
From my original notes - I based that on a post by Theodore "Ted" Ts'o, (ext3 redhat list?), end of Jan '09 (I've got the original post somewhere... damn Strigi!) - it's possible he didn't put everything into the man.
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