[PC-BSD Dev] Wild idea to speed up boot process

Claudio L. claudio at hpgcc3.org
Sat Aug 10 09:22:30 PDT 2013


On 08/10/2013 08:28, Fabrizio Parrella wrote:
> If you do it at shut down then we need to add something that checks at
> boot if it is still valid as MANY of my users like to just press the
> power button until the computer shuts off (lots of FSCK each day....
> On a side note, what is the FSCK for ZFS ? I had a computer that needs
> it with the beta version installed as it is not starting anymore)
>
Yes, I think the ram disk would need to be updated as soon as boot is 
finished.

More or less it should work like this:


* On boot, create the ram disk, and read with dd from a file in the root 
filesystem.
* Read a small file from the root filesystem that contains a list of 
files that were modified (invalidated) in the cache.
* Each file access should be mapped to the ram drive, if the file 
doesn't exist, it is read from root and copied to the ram drive.
* At end of boot, the new ram disk is dumped back into the single file, 
and the list of invalid files is cleared.
* A deamon is started that checks for any file that was included in the 
ram disk, if a file open for write then add it to the invalidated list.

And nothing needs to be done at shutdown.

Claudio


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