[CentOS] Re: Anaconda doesn't support raid10

[John R Pierce]

Ruslan Sivak wrote:
> John R Pierce wrote:
>>
>>> Well the reason not to put /boot on the same spindles as md1 has 
>>> already been mentioned a few times.  Basically flexibility.
>>> What do you mean LVM doesn't really do striping?  What does globbing 
>>> mean?  Does it mean there is no performance difference between 
>>> striping LVM and just concatenating 2 raid1's?
>>
>>
>> conventional stripesets tend to use a stripe size around 32k or 128k 
>> bytes.   LVM tends to use a fairly large PE size, often 32MB.   LVM 
>> -is- striping these PE's, if you told it to do that, but its striping 
>> with this very large chunk size, which means far fewer individual 
>> disk operation will utilize both logical drives.   If you have lots 
>> of concurrent disk accesses, this may not matter.
>> _______________________________________________
>
> The PE could be changed to a lower #.  Would this negativelly affect 
> LVM somehow?

the way LVM works, LV's -can- be built from any random set of PE's, so 
it has to use mapping tables (this is so you can grow LVs onto new space 
and so forth).    Smaller PE means more PEs, means bigger mapping 
tables.   I'm not sure I could quantify the significance of that by the 
seat of my pants.