Re: [squid-users] about ufs and aufs

On Friday 03 August 2001 11:45 pm, mani wrote:
> Hi,
>
> What is the the difference between ufs and aufs. As I know both are file
> system of the squid.In ufs mode it handles the request as single
> processes but in case of aufs it handles the request in a
> multiprocesses.. am I correct here, if not educate me.

Multiple threads. Threads are lightweight processes that share the same
memory space, making switches between them very fast. Squid also has a
multi-process storage system, diskd.

> What is advantage and disadvantages of ufs mode? What we achieve when we
> go aufs..? How these both mode works..?

Disk operations block the process making the request until the data is
available. In ufs, squid handles the io operations itself, which means it
blocks on disk IO and will not scale very far. In aufs, squid hand the io
operations off to other threads. Those threads block, but the main squid
continues normally.

The problem with aufs is threads are not well supported (either by squid
or even the OS itself) on all systems. It also incurs some CPU overhead
from squid 'tending the flock' of threads.

Redhat 7 should handle threads just fine, so use aufs if this squid will
be seeing a decent amount of traffic.

        -- Brian
Received on Sat Aug 04 2001 - 14:41:29 MDT