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Hi Everyone,<br>
<br>
I am planning to have a raid 5 array (software based) with LVM riding
atop.<br>
<br>
I have a few questions regarding the setup.<br>
<br>
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1-
<b>From Suse 10.0 Reference Manual: </b>The
physical extent size defines the size of a physical block in the volume
group. All the
disk space in a volume group is handled in chunks of this size. This
value is normally
set to 4 MB and allows for a maximum size of 256 GB for physical and
logical volumes.
The physical extent size should only be increased, for example, to 8,
16, or 32 MB, if
you need logical volumes larger than 256 GB.<br>
<br>
Is this a linear function, meaning??<br>
PE Max Size<br>
8mb 512GB<br>
16mb 1TB<br>
32mb 2TB<br>
<br>
2- Raid setup: In the following config extract, do the hard drives have
to be formatted first, or could I do like in extract 2:<br>
I assume extract 1 has the drives partitionned with type fd ( raid
autodetect)...which one is the right one!!!<br>
<b>Extract 1:</b><br>
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<pre>raiddev /dev/md0
raid-level 5
nr-raid-disks 6
nr-spare-disks 0
persistent-superblock 1
parity-algorithm left-symmetric
chunk-size 32
device /dev/sdb1
raid-disk 0
device /dev/sdc1
raid-disk 1
device /dev/sdd1
raid-disk 2
device /dev/sde1
raid-disk 3
device /dev/sdf1
raid-disk 4
device /dev/sdg1
raid-disk 5</pre>
<b>Extract 2: (using raw disk)</b><br>
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<pre>raiddev /dev/md0
raid-level 5
nr-raid-disks 6
nr-spare-disks 0
persistent-superblock 1
parity-algorithm left-symmetric
chunk-size 32
device /dev/sdb
raid-disk 0
device /dev/sdc
raid-disk 1
device /dev/sdd
raid-disk 2
device /dev/sde
raid-disk 3
device /dev/sdf
raid-disk 4
device /dev/sdg
raid-disk 5
Then mkraid /dev/md0
<b>3- Once the raid is setup, </b>
pvcreate /dev/md0
vgcreate -s16 data /dev/md0
lvcreate ( a bunch of lv's are created here)
I plan to partition the lv's with reiserfs
Some lv's will have lots of small files, where another will have tons of 700MB files.... does the PE size affect this ?
If you have any suggestion to make this setup optimal, it would be greatly appreciated. The HD's will be SATA and PATA ( mixed, but on different busses)
Thanks to everyone who will help.
Patrick Picard
Picard Consulting
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