Mirror rootvg

[rondebbs]

As I look at rootvg on several systems, I see that it is made up of two 36gb internal disks hdisk0 and hdisk1. All other VGs are on emc storage. I had always thought that hdisk0 and hdisk1 were 100% mirrored. As it turns out two logical volumes (paging00 and paging01) are on hdisk1 but not hdisk0. LG_dumplv is on hdisk0 but not on hdisk1. All other LVs including hd5 (paging) seem to be mirrored on both disks.

It appears that if I lose hdisk1 I will no longer have paging00 and paging01. If I lose hdisk0 I will lose LG_dumplv. I would like to run mklvcopy to create a mirror of those LVs but there are not enough free partitions on the disks. I'm guessing that is why they were not mirrored in the first place.

Is it common or risky to not have these LVs mirrored?

Maybe I need to add two more disks for hdisk2 and hdisk3 and add them to rootvg. In this case I would unmirror hdisk0 and hdisk1. Then leave half the LVs on hdisk0 and move the other half to hdisk1. I would then mirror hdisk0 to the new hdisk2 and mirror hdisk1 to the new hdisk3. Is this getting too messy?

Can I add 73GB drives and extend rootvg with them even though hdisk0 and hdisk1 are 36GB?

Thanks - Brad

 

[p5wizard]

For a rootvg, you need to mirror everything except the dump LVs, but there is a possibility to set up two dump devices (primary and secondary) so that a failed disk would still allow the system to create dumps on another disks should this be necessary.

To make things easier for you (less migration/unmirror/mirror activity), you can add two disks and make a separate VG for the paging spaces other than hd6. Then add/activate more paging spaces and deactivate the paging00 and paging01 in rootvg and remove these LVs from rootvg. On AIX53 it is possible to deactivate a running paging space while the system is running. On 52 and lower, this would involve a reboot.

After paging00 and paging01 are removed, you would get free space in rootvg to create an additional dump LV. See smitty dump on how to set up the primary and secondary dump LVs. I generally call them hd7x, with x being the disk number. so hd70 on hdisk0 and hd71 on hdisk1. But it can be any two names you prefer.

oh, and depending on the rootvg PP size you can add 73G disks, but then you may need to convert rootvg first to allow more than 1016 PPs per PV: e.g.

chvg -t2 rootvg

converts rootvg from max 32PVs of max 1016PPs to max 16PVs of max 2032PPs.


HTH,

p5wizard

 

[rondebbs]

I like the idea of moving paging00 and paging01 to the new disks. Unfortunately I'm at 5.2 so I'll have to squeeze in a reboot at some time for my 24/7 system.

Regarding lg_dumplv that is currently using 48 PPs on rootvg/hdisk0 - can I also move this out of rootvg and onto the new disks? I'm just not sure whether some of these LVs need to stay on rootvg for some reason.

Thanks - Brad

 

[p5wizard]

Apparently swapoff command is also available on AIX52. But see if you can do it on a test system first. I've only ever deactivated a swapspace on AIX53.

The primary dump device must be in rootvg and must be unmirrored, so for 2 mirrored disks in rootvg, I generally create a 'mirror image' of the lg_dumpdev on the other rootvg disk.


HTH,

p5wizard