Re: [gentoo-user] RAID-0 with LVM - is there any point?

[Daniel Iliev <danny@ilievnet.com>]

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Daniel Iliev wrote:
> Neil Bothwick wrote:
>   
>> On Thu, 05 Apr 2007 17:39:06 +0300, Daniel Iliev wrote:
>>
>>   
>>     
>>> Out of curiosity I made some tests which confirmed my expectations. What
>>> about you - did you have time (and wish) to take some performance
>>> benchmarks? I would be glad to see some additional results.
>>>     
>>>       
>> So your tests show that RAID-0 is faster than LVM, but I'll be using LVM
>> anyway so the comparison will have to be between LVM+RAID and LVM alone.
>> I haven't had a chance to do this yet, hopefully over the holiday weekend.
>>
>>
>>   
>>     
>
> OK
> I still have that free space and I'll post the results of the same test
> against RAID0+LVM.
>
>   

Here we go. I think the results can't be interpreted unambiguously.
Perhaps I'll use a benchmarking program in the weekend to get clearer
results.

-- 
Best regards,
Daniel



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echo y | mdadm -C /dev/md9 -n2 /dev/sda11 /dev/sdb11 -l0
pvcreate /dev/md9
vgcreate test /dev/md9
vgdisplay | grep 'Total PE'
  Total PE              1686
lvcreate -i2 -l1686 -nlogvol test 
  Using default stripesize 64,00 KB
  Number of stripes (2) must not exceed number of physical volumes (1)
//ooops! :) //
lvcreate  -l1686 -nlogvol test 
  Logical volume "logvol" created

mkfs.xfs /dev/test/logvol
mount /dev/test/logvol /test
time cp /test.rnd /test

real    0m54.547s
user    0m0.046s
sys     0m7.118s

sync

time mv /test.rnd /test

real    0m46.863s
user    0m0.067s
sys     0m7.045s

sync

time mv /test/test.rnd /

real    1m27.282s
user    0m0.063s
sys     0m13.456s


BOTTOM LINE:

(LVM and RAID-0 are taken rom the prev. tests. The new one here is only RAID-0+LVM)

cp /test.rnd /test
LVM:      20.78 [MB/s]
RAID-0:   33.41 [MB/s]
RAID+LVM: 27.49 [MB/s]

mv /test.rnd /test

LVM:      29.04[MB/s]
RAID-0:   31.56[MB/s]
RAID+LVM: 32.00 [MB/s]

time mv /test/test.rnd /
LVM:      17.089 [MB/s]
RAID-0:   27.84[MB/s]
RAID+LVM: 17.185 [MB/s]