Internal Disk configure in Raid-5 in p520

[cts123]

Hi,

We have one P520 server with AIX5.3. At present it has two internal disk ( 36GB ecah) and its using for rootvg which is mirrored.

We want this machine to use as a TSM server and want to put 6 additional HDD ( 146GB ) in that internal bay and want to use for TSM diskpool. And also want to make RAID-5 for these 6 disks. Is that possible?

How can I start ?

TIA.

 

[khalidaaa]

Hi Sam,

As far as i know, there are 8 disk bays inside the p5 520. You are using only 2 for now so 6 are free for you to use!

In theory, This can be done but to be honest i don't have that much experience with the TSM. I remember we had TSM long time back and i was administering it but there was a tape library and optical library too. So it depends on how you configure the TSM and on the backup space requirement.

Regards,
Khalid

 

[cts123]

Khalid,

I agree with you. And we are actually going for 6 disks only to put them in the bay. I was actually looking for all 6 disks under RAID-5.

Whole plan is, will create a separate VG ( say tsm-vg) and will create the LVs ( for diskpool). All these thing I was planning to make under RAID-5.

If I get the disks and start creating VG, I can make that VG mirrored ( RAID-1). By simply mirrorvg command.
In that case I may go for RAID-1 or maxm. RAID10. In these cases I will loose 3 disks.

If I could go for RAID-5, I could use 5 disks space. Correct me if I am wrong.

Regards,

-Sam

 

[khalidaaa]

You are absolutely right. But i'm not sure how would you connect the disks to be RAID-5!

I think you need to implement the RAID-5 somehow in hardware.

I remember i managed to do this on a SAN (DS4300) But never on internel disks!

I would advice you to talk to IBM with that!

Regards,
Khalid

 

[DukeSSD]

I think the p520 had two 4 way disk backplanes, which are connected to either the 2 onboard scsi controllers, or via 2 raid enablemant cards.

As far as I know you need the raid enablement card to use raid 5 and you cannot create an array over more than one card / backplane.

So you will not be able to create a raid 5 array across 6 disks.

If you NEED that much space I think you will need to buy a raid enablement card and use 300GB disks in the second disk bay and leave the rootvg in the other adapter / disk backplane.

 

[cts123]

Got the point ..Thanks to DukeSSD & Khalid.

Here is the system output.

# lscfg | grep -i pci
Model Implementation: Multiple Processor, PCI bus
* pci1 U787A.001.DPM0M49-P1 PCI Bus
* pci11 U787A.001.DPM0M49-P1 PCI Bus
* pci9 U787A.001.DPM0M49-P1 PCI Bus
* pci7 U787A.001.DPM0M49-P1 PCI Bus
* pci8 U787A.001.DPM0M49-P1 PCI Bus
+ sisscsia0 U787A.001.DPM0M49-P1 PCI-X Dual Channel Ultra320 SCSI Adapter
+ scsi0 U787A.001.DPM0M49-P1-T10 PCI-X Dual Channel Ultra320 SCSI Adapter bus
+ scsi1 U787A.001.DPM0M49-P1-T11 PCI-X Dual Channel Ultra320 SCSI Adapter bus
* pci10 U787A.001.DPM0M49-P1 PCI Bus
* pci0 U787A.001.DPM0M49-P1 PCI Bus
* pci4 U787A.001.DPM0M49-P1 PCI Bus
* pci5 U787A.001.DPM0M49-P1 PCI Bus
* pci2 U787A.001.DPM0M49-P1 PCI Bus
* pci3 U787A.001.DPM0M49-P1 PCI Bus
+ ent0 U787A.001.DPM0M49-P1-T5 2-Port 10/100/1000 Base-TX PCI-X Adapter (14108902)
+ ent1 U787A.001.DPM0M49-P1-T6 2-Port 10/100/1000 Base-TX PCI-X Adapter (14108902)
* pci6 U787A.001.DPM0M49-P1 PCI Bus

In this case scsi0 and scsi1 are using for internal disk.


# lscfg | grep -i dis
+ hdisk0 U787A.001.DPM0M49-P1-T10-L5-L0 16 Bit LVD SCSI Disk Drive (36400 MB)
+ hdisk1 U787A.001.DPM0M49-P1-T10-L8-L0 16 Bit LVD SCSI Disk Drive (36400 MB)

# lscfg | grep -i sc
+ sisscsia0 U787A.001.DPM0M49-P1 PCI-X Dual Channel Ultra320 SCSI Adapter
+ scsi0 U787A.001.DPM0M49-P1-T10 PCI-X Dual Channel Ultra320 SCSI Adapter bus
+ hdisk0 U787A.001.DPM0M49-P1-T10-L5-L0 16 Bit LVD SCSI Disk Drive (36400 MB)
+ hdisk1 U787A.001.DPM0M49-P1-T10-L8-L0 16 Bit LVD SCSI Disk Drive (36400 MB)
* ses0 U787A.001.DPM0M49-P1-T10-L15-L0 SCSI Enclosure Services Device
+ scsi1 U787A.001.DPM0M49-P1-T11 PCI-X Dual Channel Ultra320 SCSI Adapter bus




# lsdev -Cl hdisk0 -F parent
scsi0

# lsdev -Cl hdisk1 -F parent
scsi0

Both the disk hdisk0 and hdisk1 are in scsi0.

# lsdev -Cl scsi0 -F parent
sisscsia0

# lsdev -Cl scsi1 -F parent
sisscsia0

# lsdev -Cl sisscsia0 -F parent
pci8

# lsdev -Cl pci8 -F parent
pci1

# lsdev -Cl pci1 -F parent
sysplanar0

So, RAID1 or RAID10 is possible. But RAID5 is not possible.
I can put 4 disks in scsi1 and use them as RAID10.

If we go for DS4300 option, We may have to think in different angle. As at this point of time, there is no FC adapter present in the system.

Regards,

-Sam

 

[RodKnowlton]

If there's a possibility you'd want to upgrade to larger disks at some point using the internal bays, you might want to make two RAID0 devices and mirror them in LVM.

The advantage being that you retain the option to un-mirror and remove one of the RAID0 devices (both logically and physically) so that larger drives can be placed in those two slots.

If you tie up all four in RAID10, you won't have any way to upgrade the drives in situ and won't really gain that much in terms of performance or reliability.

Just my 2 cents.

- Rod




IBM Certified Advanced Technical Expert pSeries and AIX 5L
CompTIA Linux+
CompTIA Security+

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[normntwrk]

I did pretty much what you want with a 550 using the hardware RAID enablement card - all drives are internal

sisioa0 08-08 Available PCI-X Dual Channel U320 SCSI RAID Adapter

hdisk2 08-08-ff-0,0 Optimal RAID 5 Array 285.5GB
pdisk1 08-08-00-5,0 Active Array Member 71.4GB
pdisk0 08-08-00-8,0 Active Array Member 71.4GB
pdisk2 08-08-01-3,0 Active Array Member 71.4GB
pdisk3 08-08-01-4,0 Active Array Member 71.4GB
pdisk5 08-08-01-8,0 Active Array Member 71.4GB

pdisk4 08-08-01-5,0 Active Hot Spare 71.4GB
[MORE...4]
hdisk0 08-08-00-3,0 Available 16 Bit LVD SCSI 73.4GB
hdisk1 08-08-00-4,0 Available 16 Bit LVD SCSI 73.4GB


Norm