Re: 6618 drives for model 270 -- MIDRANGE-L

Well my guess is that one of two things occurred with the BCC drives. I) They did the math on power and heat and came up 'close enough' to IBMs 10K drives so that they didn't feel that there would be any issues or II) They ignored it, tried it, and didn't have any issues. In either case if it works they win and their customer's win. If there was a failure though of a PS for example then who gets that finger pointing game? Since I've not heard of this particular problem I suspect that they did 'I)' above.

If your drives performed well that's great because they did what you expected. The drive cages in the 270 and it's side-car aren't the fastest out there however so under sustained load with 6 drives in the can you likely couldn't push the drives to their full extent. If you never needed that then you win of course. The FC #0595/5095, EXP24 and the like support full Ultra320 speeds. I believe the 270 supported only Ultra160 possibly only 80Mbps.

And yes Ohms law says that half the disks at twice the power is the same draw as twice the disks at half the power, BUT if you had 6 of the 'twice the power' drives all in the CEC then you're taxing that PS. If you had four over there and 6 over in the side car (preferably 3 in each of the two cans) then you did good and everybody is happy.

- Larry

Wilt, Charles wrote:

Joe,

At a prior place of employment, we chose to use BCC drives in our new 270.

IIRC, they were the 15K ones in addition to being configured for 1/2 capacity (FAST as BCC calls it).

I forget now how many we had, 8 or 10 maybe? We did have the 270 sidecar attached.

Had one fail over the years, but other than that no issues. The box is still running v5r2 right now.
However, the BCC drives have were replaced this year by IBM drives simply because BCC wasn't
particularly responsive when they looked to add drives.

Not to take anything away from Larry with respect to the power requirements. But the reason we went
with BCC is that we only needed 10 BCC disks to get the performance that would have required 19(?) IBM
disks. I'm not an Electrical Engineer ;-) But it seems to me that 1/2 the disks at twice the power
isn't all that bad. Larry, you've got more experience, any comments?

Charles

-----Original Message-----
From: midrange-l-bounces@xxxxxxxxxxxx [mailto:midrange-l-bounces@xxxxxxxxxxxx] On Behalf Of Joe Pluta
Sent: Monday, August 13, 2007 11:13 AM
To: 'Midrange Systems Technical Discussion'
Subject: RE: 6618 drives for model 270

Well this just sucks.

The primary reason I want to go with the BCC drives is that they are 15K drives rather than the 10K IBM drives. This machine tops out at V5R4; I wonder if I should just apply V5R4 and the latest cumes and then never apply another PTF.

Speaking of PTFs, isn't that what A and B sides are for? Isn't there a procedure to apply a PTF and if it smokes, to go back to the pre-PTF state?

Joe