Re: where is the journal kept?

[David Masover <ninja@slaphack.com>]

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Shawn Rutledge wrote:
> On 8/16/05, Hans Reiser <reiser@namesys.com> wrote:
> 
>>Reiser4 does a very nice job of packing the tree tightly, which is
>>independent of seeks.  Ditto for compression plugin.
>>He merely needs to ignore some code, he is not harmed by it.  If he
>>wants to write a new block allocator, sure, why not, we have allocator
>>plugins yes?   His will just be simpler.....
> 
> 
> But the most important thing is to reduce the number of writes as low
> as possible.

Something Reiser4 does very well.  If you have enough RAM, it's possible
to avoid any reads/writes at all -- given enough RAM, it behaves as a
ramdisk, which is why I wish I knew how to tell Gentoo to *not* mount
tmpfs over /dev.

One other thing you might try is disabling the write-twice behavior.
Currently, if you've got a huge, fairly well-sorted file that you're
making lots of tiny writes to, such as a database, it makes sense to
write twice to keep the file from getting fragmented.  But,
fragmentation isn't nearly as much an issue on truly random-access
media, so you'd want the default small-file behavior to be used
everywhere -- first write the data to the new location, then atomically
update the pointer to it as you deallocate the old location.

Am I right about this?  I'm not feeling very lucid today...
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