RAID 5 configurations on HP-UX

[amme]

Hi, i had search through this forum about the RAID 5 configurations on HPUX server (model RP5470) but there is no thread about it

from another forum, there are some configuration that might help me to configure the RAID 5, configurations that i get as below:

configurations for RAID 0
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#!/bin/sh
pvcreate -f /dev/rdsk/c4t1d0
pvcreate -f /dev/rdsk/c1t1d0

mkdir /dev/vg01
mknod /dev/vg01/group c 64 0x0a0000

vgcreate -p 128 /dev/vg01 /dev/dsk/c4t1d0

vgextend /dev/vg01 /dev/dsk/c1t1d0
# -i represents number of drives you are stripping across
lvcreate -i 2 -I 128 -n lvol1 -r N /dev/vg01

lvextend -l 2046 /dev/vg01/lvol1 /dev/dsk/c4t1d0 /dev/dsk/c1t1d0

newfs -F vxfs /dev/vg01/rlvol1
fsadm -F vxfs -o largefiles /dev/vg01/rlvol1

mkdir /raid0filesystem

mount /dev/vg01/lvol1 /raid0filesystem

exit

configurations for RAID 1
****************
#!/bin/sh
pvcreate -f /dev/rdsk/c4t1d0
pvcreate -f /dev/rdsk/c1t1d0

mkdir /dev/vg01
mknod /dev/vg01/group c 64 0x0a0000

vgcreate -p 128 /dev/vg01 /dev/dsk/c4t1d0

lvcreate -n lvol1 /dev/vg01
#extents number will vary
lvextend -l 1023 /dev/vg01/lvol1

newfs -F vxfs /dev/vg01/rlvol1
fsadm -F vxfs -o largefiles /dev/vg01/rlvol1

mkdir /raid1filesystem

mount /dev/vg01/lvol1 /raid1filesystem

vgextend /dev/vg01 /dev/dsk/c1t1d0
#this part may take a while...the more you mirror the longer it takes
lvextend -m 1 /dev/vg01/lvol1

exit


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here is my pre-configure RAID 5

pre-configurations for RAID 5
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#!/bin/sh
#minimum disk for RAID 5 required = 3
pvcreate -f /dev/rdsk/c4t1d0 <--disk1
pvcreate -f /dev/rdsk/c1t1d0 <--disk2
pvcreate -f /dev/rdsk/c2t1d0 <--disk3

mkdir /dev/vg01
mknod /dev/vg01/group c 64 0x0a0000

vgcreate -p 128 /dev/vg01 /dev/dsk/c4t1d0

lvcreate -n lvol1 /dev/vg01
#extents number will vary
lvextend -l 1023 /dev/vg01/lvol1

newfs -F vxfs /dev/vg01/rlvol1
fsadm -F vxfs -o largefiles /dev/vg01/rlvol1

mkdir /raid5fs

mount /dev/vg01/lvol1 /raid5fs

vgextend /dev/vg01 /dev/dsk/c1t1d0

lvextend -m 1 /dev/vg01/lvol1

exit

mount /dev/vg01/lvol1 /raid5fs

exit
*************************

for your information, my HP-UX server (model RP5470) had its RAID card attached to it, so, the server should can configure RAID 5 without any problem. Right now, i had manage to modify the configuration so that it would be run as RAID 5... but i dont know whether it can be act like i want or not, or how i want to make sure that it run as RAID 5 or not..

hope someone could help me on this.

[Torsten. · Accepted solution]

So do you have a hardware RAID controller?

Check in ioscan!

Just in case it is a RAID4si, the management tool is "irm".

[Duncan Edmonstone]

You seem to be failing to understand the difference between hardware RAID and software RAID.

Logical volume manager (all the pv*, lv* and vg* commands you've been running) implements Software RAID, but does _not_ support RAID 5, it can do RAID0 and RAID1 only (plus some pseudo-RAID1+0 stuff if you fiddle about enough with it)

In your system you mention you have a RAID card - this is hardware RAID - completelt different to LVM and works at a much lower level - Torsten has pointed you at the tool to use to manage that.

For hardware RAID, once a RAID device has been created it will appear as just another disk device (/dev/dsk/cXtYdZ) which you can then use directly or put under LVM control.

HTH

Duncan

[Hein van den Heuvel]

amme,

Your question suggests that you want to implement in software. That is a "bad idea", because a well performing raid-5 requires specialized, and battery backup protected, caches to assists.

You want to build on top of HARDWARE provided raid-5, as others mention.

also... fwiw... while 3 is indeed the minumum number of disks to do raid-5, it is again a 'bad idea' only to be considered when there are no alternatives (no more drive slots).
Using 3 disks, the storage space overhead for raid-5 is 33% (1/3). You might as well using raid-01 with 50% storage overhead (1/2) but 100% more performance potential.

hth,
Hein van den Heuvel
HvdH Performance Consulting.




http://forums11.itrc.hp.com/service/forums/questionanswer.do?threadId=1168258

[Jaime Bolanos Rojas.]

It looks like you got the answer, in HP-UX using LVM you can only build a Raid 1, and even that is done at the logical volume level and not the hard drive level.
Any other option is HW Array and software does not really care about the way that the HW controls the redundancy.

Regards,

Jaime.

[Patrick Wallek]

The steps you give in your "pre-configurations for RAID 5" section do NOT set up a RAID 5 file system. All this section is doing is creating an LV that will span 3 disks IF NEEDED. The way this is set up, when you create an LV, it will use all space on disk1, then disk2 then disk3. That is all. Absoulutely positively No RAID 5 here!

As said by others, if you have a RAID card installed, you need to use the appropriate utilities with it to configure hardware RAID.

[amme]

thanks everyone helping me understanding about RAID, i'll read more about it... about irm, i had try and now try to figure out its documentation...

thanks again.