Re: where is the journal kept?

[Hans Reiser <reiser@namesys.com>]

David Masover wrote:

> 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...

Yes, but there is not a lot of write twice for most usage patterns....

Hans