spreading partitions over multiple drives

[Willem Jan Withagen]

Geert Hendrickx wrote:

>>Not for this usage.
>>    
>>
>>>Fragmentation may be LESS of a problem with UFS, but a moving target
>>>like one big /usr (incl src, obj, ports) will get fragmented as well.
>>>      
>>>
>>This is how you see it. I have not heard that there is any tool to help 
>>here.
>>
>>I would not call this fragmentation. It is more like spreading the files 
>>from one directory all over the disk.
>>    
>>
>
>Ok but the effect is the same: constant movement of the head.  
>  
>
I would expect a bigger system to cache just about all file access 
during 'make buildworld'.
Even when building things with -j 64 I can not get my dual-opteron 1Gb 
system  get without free pages.
And as such most files will only be read once, and object output will be 
"slowly" synced on the disks.
Disk I/O rearly becomes the bottleneck, most of the time I'm missing raw 
CPU cycles.
And I have everything on 1 large 200Gb disk.

>>>Splitting up partitions would reduce this fragmentation (as you are
>>>essentially defining some "super large blocks"), and may increase
>>>filesystem stability in case of crashes etc.  
>>>
>>>      
>>>
>>It might not affect stability but it increases the chances to fix a 
>>problem in case of a crash.
>>    
>>
>
>Yes I meant stability of the filesystem not of the running OS.  
>
>
>Ok but the original question was about spreading partitions amongst
>multiple disks, not pro/con splitting partitions on one disk. :-)  
>  
>
My major problem with a lot of partitions has always been that one way 
or antoher I outgrow a partition and then all of a sudden the logic 
needs to be skewed for space reasons. Finaly disks start to grow to the 
size where this becomes a moot point. 10Gb for /usr will last me until 
we get to the next step of disk-sizes.

Having things on different spindles will of course be a major plus.

--WjW