Second p410i with 512 BBWC controller for DL 380 G6

[myg_1]

Hello!

We want to obtain HP DL 380 G6 server for virtualization. We plan to install 8 146GB SAS 15k disks.
In spite of the fact that HP DL380 already has
a p410i internal scsi controller, we want to install additional p410 controller (http://h10010.www1.hp.com/wwpc/uk/en/sm/WF06c/A1-329290-332469-3965957-3965957-3883890-3883935.html) to increase the disk performance. The idea - to assign 4 SAS SFF disks to one scsi controller and the other 4 SAS SFF disks to second scsi controller. Is it possible?

Thank you for any help!

[Erdogan Temur]

Yes,You can use both array controller together.

[myg_1]

Thank you.
Should I obtain additional kit\cables to external p410 controller?

[Erdogan Temur · Accepted solution]

Hi,

HP Smart Array P410/512 MB with BBWC Controller kit part no : 462864-B21

This is how we thank each other in the forum

http://forums11.itrc.hp.com/service/forums/helptips.do?#33

Regards.

[myg_1]

Do I need any SAS cable between p410 and hdd bay? SAS to miniSAS cables?

[myg_1]

From the HP Smart Array Controllers for HP ProLiant
Servers
User Guide:

"Use the internal wide SAS cable provided with the server to connect the controller to the drives"

Who knows what Part Number of the cable that I should install to connect p410 controller with SAS bays ?

[Erdogan Temur]

Hi,
Cable part list.

Mini-SAS to SFF8484, 18.00"
496015-B21
Mini-SAS to SFF8484, 24.00"
496015-B21
Mini-SAS to SFF8484, 32.00"
496016-B21
Mini-SAS to SFF8484, 35.00"
496016-B21

Regards.

[TTr]

> The idea - to assign 4 SAS SFF disks to one scsi controller and the other 4 SAS SFF disks to second scsi controller.

You should be able to use one of the P410i cables and move it to the new P410. See page 62 in user guide http://bizsupport1.austin.hp.com/bc/docs/support/SupportManual/c01705681/c01705681.pdf
One caveat is if the P410i cable is to short and does not reach the new P410 connector.
It should be long enough, the new P410 has the connectors at the end of the card
http://h18000.www1.hp.com/products/quickspecs/13201_div/13201_div.html
If it does not work the cabling options are in the quickspecs.

However before you invest the extra money for the add-on controller you have to realize the the P410i/P410 have 8 independent disk ports for i/o and you will be using only 4 of them. For each controller you will be cutting down the i/o to a half.

You are adding processing power by using two controllers but at the same time using half of the i/o ports might starve the controllers from disk i/o and make them inefficient.

This one potentially can go either way, better or worse. There are other factors that may influence this and have to do with the type of i/o, short and frequent i/o or long and sustained.

[myg_1]

Hello TTr!

Thank you for smart analysis.

I think you are right - with two controllers and 8 disks I will utilize only a half of the controller's power.

Because running several virtual machines on one physical server may lead system to disk intensive operations, so I need a way to be insured for future disk i\o problems.

Anothe solution - to upgrade SAS controller's BBW cache up to 1 GB (from 512). But I'm not sure that p410i can be upgraded. I have found in p410 documentation only "REPLACE" BBWC procedure, rather then "UPGRADE", i.e. I must remove preinstalled 512 cache from controller and install instead of it the cache with larger size, for instance 1 GB?

Am I right?

[TTr]

Adding more cache to the controller will help. I would start with one controller P410i and see how it goes. Later on you can expand by adding a second 8-disk cage - the G6 can go up to 16 internal disks - and use a P410 for the second set of 8 disks.

The raid setups in general are very flexible, you can build them for capacity or build them for performance or anything in between. The idea here (performance) is to have a minimum number of LUNs on the controlelr so that the i/o is served up. If the controller can not keep up with the i/o then you add another controller with more LUNs. Also in a perfromance setup you don't need large disks. Most of the time you need a large number of disks to get the i/o performance but you barely use up their capacity. (For capacity set ups you would use the largest possible size disks).

What is the balance and how many LUNs you should create, only you can determine that based on the character of the i/o.

Next you need to consider raid types, would raid5 be sufficient or would you need raid10? That's something else you should start looking into.