[nagar_yash]

Hi All

I have a VG of 4 disks, all the physical volumes are RAID5 from the storage appearing a LUNs.

Now i want add a PV which is RAID1 to that VG. is it ok? to add and mix the RAIDs in a single VG, what are other implications. performance etc?

This AIX box has the LUNs mix of RAID1 and RAID5.


Rgds
Yash

[ross.mather]

Assuming they are all LUNs the performance won't chnage much at all. Dependent on the Storage server the performance difference is probably aroung the 5% mark. Remember that most of these devices have big caches to avoid write penalties.

[Frans]

You can add any disk to a volume group but there are some considerations you have to take in to account.

if you add disk that has mirror or raid or none at all and you lose one of the disks this will impact your vg. You have to decide how you want your system to react
Always use best possible layout and try to stick to this as a principle.
The vg is only as protected as you make it
If you have file system that is not important you can add disk that is not mirror or raided to that VG and make file systems from this.

[nagar_yash]

All the LVs in that VG ( formed with RAID5 disks, before i add RAID1 disk), are mirrored.

We have tested this, made a VG of RAID5 disk, then successfully added the RAID1 disk, it worked. But not sure if there would be any significant performance issues, though as you said, 5%, i will remember it. it is Ok for me.

The LV which we need to be extended after we add RAID1 will be oracle archive logs, which i believe would not be requiring too many disk IO. So i think it would be Okay to go about it.

Anyways, thanks for your help!!

Rgds
Yash