Steps in Installing an EVA5K Expansion - 0C6D w/ 72xFATA-400

[Alzhy]

We're getting an expansion Cabinet for our aging EVA5K (VCS 3.028). It is supposed to come with 72 x 400GB FATA drives.

My Question.

1. Will the install be disruptive?
2. After the HP Engineer does his install/hook-up of the FC Cables to the loop switches on the main cabinet, will the disks already appear to be customizable as a DISKGROUP?
3. How long to create a DISKGROUP?
4. What's the optimal configuration? Do we create just one big Diskgroup out of these 72 drives or 2 Diskgroups?


Thanks!

[Nigel Poulton · Accepted solution]

You could ask you installation engineer to either create a new Disk Group with the new disks or leave them ungrouped so that you can create the groups(s) according to your needs. Also, if these are your first FATA drives in the system then they will have to go in their own Disk Group and cannot be added toa Disk Group with high performance FC disks.

When deciding how many disks to have in a disk group on an EVA, more is better. You can get better performance from a single disk group with 72 spindles than with two Disk Groups with the disk divided among them. This is because the more spindles in the disk group the better the back end I/O performance.

Having multiple Disk Groups can also be more wasteful of space as you need to set aside capacity for sparing per disk group. Also you can sometimes get stranded capacity in disk groups.

Also another good reason for having a DG with 72 spindles in it is that 72 is divisable by 8, and it is always recommended that the number of disks in a DG is a multiple of 8 because of the way that RSS sets are configured (this is done automatically by VCS).

As far as how long it will take to create the Disk Group - Im pretty sure this is not a long process but its done as a background task so as not to disrupt normal I/O. You just give the Disk Group a name, tell it how many disks, set a protection level and an occupancy alarm level and clock finish.

mackem

[Steven Clementi]

Nelson:

1. Adding in a 0C6D should not be disruptive as long as all 6 shelves are NOT plugged into the Back-End Loop Switches all at once. Adding a single shelf to the system should be relatively non-disruptive, though I always suggest you plan for a window of downtime. I never like performing upgrades like where something can go wrong during an operational period.

2. The disks and shelves will appear in COmmand View just like the other 12 shelves, numbers 13-18. You should be able to do to them, whatever you want within the confines of Command View EVA.

3. The same amount of time it takes to create any other diskgroup, assuming you have been through the process before. If you haven't, the diskgroup creation process is not very long... a couple of minutes maybe? I have not created anything larger than 24 or so drives and that takes maybe 10 to 20 seconds, IF that.

4. HP's "best performance" answer is to have only 1 diskgroup on your eva. If your existing 2C12D has High Performance Fibre Drives (not FATA), then you are stuck having to create a new Disk Group. If you have an existing "Near-Online" disk group(FATA drives), then you can either ADD the disks to the existing disk group, or create a new one.

I agree with keeping the disk group total disks at a multiple of "8".


Steven

[Alzhy]

What we got was actually a 0C4D.. the 4 Shelves were numbered 15-18 and we got 48 500GB FATA Drives distributed as follows:

Shelve 18: 12
Shelve 17: 11
Shelve 15: 13
Shelve 14: 12

There is however these puzzling observations. CommandView under "Ungrouped Disks" show only 40 disks. In Diskgroup creation Wizard - Advanced, despite selecting 40, the diskgroup is created with just 32 drives! Is this normal? I had to manually add the remaining 8 disks. But what puzzles me more is where did my other 8 disks go?

Mor puzzling is on another EVA that was hooled up to a similarly configured 0C4D, same disk population and disk count. COmmandView only shows 36 Ungrouped disks out of the 48! And with the Diskgroup creation wizard it only initially set up 28 drives again forcing me to manually add the remaining 8. On this EVA we are missing 12 drives? Is this normal?

[Uwe Zessin]

CV-EVA sometimes gets confused and creates duplicate names. I am sure the disks are there if you check the hardware folders.

I would check with SSSU - do a:
> ls disks

and look for any disk whose names have suffixes like "{1}".

[Alzhy]

Thanis Uwe.

I can indeed see the 4 added shelves and the 48 drives in Hardware view but inthe Ungrouped disks - they did not total 48. And I've been only able to configure in 40 disks on our 1st EVA. On the seconds, same thing but with even less number of disks configured to the Diskgroup -- 36 instead of 40 as the other EVA with 12 "missing" disks...

Am about to raise a ticket with HP...

[Tom O'Toole]

We rename our disks here based on bay and enclosure. The CV/eva default names are effectively random, and as Uwe said, sometimes duplicates come up (at one point we had about 30 "disk 1000"s. But, you can rename them from the gui or using SSSU. Here's an (OPENVMS) example script that helps with the renames them...

[Alzhy]

The fix suggested by HP and worked - restart Command View Services. Problem fixed.