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Re: raid 5 : partitioned array VS lvm



Alex Samad <alex <at> samad.com.au> writes:

> > Lately I tried some different configurations (lvm & partition) to divide 
> > my raid
> > 5 array. 
> you might want to check out http://www.miracleas.com/BAARF/BAARF2.html talks 
> about why you might not want to use raid5 in this config and maybe raid1/0

Thank you for the information. I read few articles but I'm not a company, and
raid1/0 is too expensive for me. 

Anyway, it does not explain why there is so much performance differences between
lvm and partitioned array. 

Here is some additional information : 

# pvdisplay 
  --- Physical volume ---
  PV Name               /dev/md0
  VG Name               raidvol1
  PV Size               1,34 TB / not usable 0   
  Allocatable           yes (but full)
  PE Size (KByte)       65536
  Total PE              21908
  Free PE               0
  Allocated PE          21908

# vgdisplay
  --- Volume group ---
  VG Name               raidvol1
  System ID             
  Format                lvm2
  Metadata Areas        1
  Metadata Sequence No  11
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                3
  Open LV               3
  Max PV                0
  Cur PV                1
  Act PV                1
  VG Size               1,34 TB
  PE Size               64,00 MB
  Total PE              21908
  Alloc PE / Size       21908 / 1,34 TB
  Free  PE / Size       0 / 0

# lvdisplay 
  --- Logical volume ---
  LV Name                /dev/raidvol1/data1
  VG Name                raidvol1
  LV Write Access        read/write
  LV Status              available
  # open                 1
  LV Size                849,25 GB
  Current LE             13588
  Segments               1
  Allocation             inherit
  Read ahead sectors     0
  Block device           253:0
   
  --- Logical volume ---
  LV Name                /dev/raidvol1/data2
  VG Name                raidvol1
  LV Write Access        read/write
  LV Status              available
  # open                 1
  LV Size                500,00 GB
  Current LE             8000
  Segments               1
  Allocation             inherit
  Read ahead sectors     0
  Block device           253:1
   
  --- Logical volume ---
  LV Name                /dev/raidvol1/home1
  VG Name                raidvol1
  LV Write Access        read/write
  LV Status              available
  # open                 1
  LV Size                20,00 GB
  Current LE             320
  Segments               1
  Allocation             inherit
  Read ahead sectors     0
  Block device           253:2



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