On 12/14/10 9:41 PM, Ross Walker wrote:
> On Dec 14, 2010, at 7:01 PM, Les Mikesell<lesmikesell@xxxxxxxxx> 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@xxxxxxxxx
_______________________________________________
CentOS mailing list
CentOS@xxxxxxxxxx
http://lists.centos.org/mailman/listinfo/centos
