On 12/14/10 9:41 PM, Ross Walker wrote: > On Dec 14, 2010, at 7:01 PM, Les Mikesell<lesmikesell at gmail.com> wrote: > >> On 12/14/2010 5:14 PM, Markus Falb wrote: >>> >>>> >>>> But this only helps if you don't know where you will need to grow. If >>>> you know it is going to be under /var, just give it all the space you >>>> have in the first place and avoid the overhead of lvm. >>> >>> To quote Jason, the OP: "what should my SWAP space be" ? >>> How should I know ? lvm to the rescue. >> >> I've never seen a machine that had pushed 2 gigs into swap recover (i.e. >> whatever was consuming the memory did it faster than jobs could complete >> and release any). Increasing performance might have saved them but not >> adding more swap. >> >>> lvm also helps if you want to have additional partitions. Maybe one day >>> you recognise that a separate partition for /var/log/httpd would be a >>> good thing. >>> >>> You are talking about the performance overhead ? Not sure about that. I >>> think the flexibility you gain makes it at least worth thinking about >>> it. Said that, I would be interested in hearing about disadvantages of lvm. >> >> It really depends on the purpose of the machine. If it has to be a high >> performance server, I wouldn't want any extra overhead and I certainly >> wouldn't want bits and pieces of a partition to be spread into chunks >> far apart on the disk. It would be even better to put the busy content >> on separate drives to avoid seeks as much as possible. > > LVM overhead is negligible. It is basically a kernel mapping of virtual memory space into 4MB+ extents across drives. > > It basically has the same overhead as Linux's virtual memory subsystem. Maybe, if memory access time was measured in many milliseconds to move chunk to chunk... -- Les Mikesell lesmikesell at gmail.com