RE: 6618 drives for model 270

So are there actual specs out there that I can read and do the math on
myself to make a reasoned determination? This is a "back release" machine,
but I also want to use it as my stable production box. My production is
little more than my website and demos, so I won't go out of business if it
craters (and I'll be sure to have a failover configuration on my development
box), but it's also damned inconvenient to lose everything.

I'm far less worried about microcode than about heat and power. I'll be
sure to do full backups every time I go to apply PTFs, and since I will now
be a freaking full-metal admin dude after John helps me load the OS, a
second load would be no big deal.

But if the disks are likely to fry the whole damned box and take everything
down with it, I'm not particularly thrilled about the concept. I'm not
getting a clear sense here whether the BCC drives "ARE" or "COULD BE" bad.
Larry, you say you had problems but the paragraph below intimates that the
drives might be just ducky.

I'd be a lot more comfortable one way or the other if there were actual
technical specs to look at.

Joe

From: Larry Bolhuis

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