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Mixing drive types in MSA1000

Manoj_28
Advisor

Mixing drive types in MSA1000

I am planning configure an MSA1000 like this

First array which will have 8nos of 10K RPM disks which spread across all for scsi channel and second array which will have 8nos of 15K rpm hard disks which again spread across all four scsi channels of MSA1000.

Whether I will get better performance on the second array?

Regards
Manoj
7 REPLIES
Jefferson Humber
Honored Contributor

Re: Mixing drive types in MSA1000

Manoj,

If all the drives in the array have the same characteristics, and evenly distributed..... then yes it should give higher performance than the other slower array.

I assume the RAID setup will be the same ?

Jeff
I like a clean bowl & Never go with the zero
Manoj_28
Advisor

Re: Mixing drive types in MSA1000

Thanks Jeff,

My question is as the same SCSI bus holding 10K rpm and 15 K rpm disks, whether the speed will reset to the lower one.

Regards
Manoj
Uwe Zessin
Honored Contributor

Re: Mixing drive types in MSA1000

No, the 'SCSI bus speed' has nothing to do with the disk drives RPMs. You can't do 'spindle sync' between different models anyway.

On SmartArray controllers, the transfer speed is individually negotiated between the controller and the disk drive, so an Ultra-2 disk drive will transfer with U2 speeds, but a U320 disk drive can transfer with U320 speeds if the controller permits it. As the MSA1000 can't do that - it will just transfer with U3 speed, but not get told to switch down to U2.

Other controllers, e.g. from pre-merger HP behave differently, I got told. Still, a 10k drive will rotate with 10kRPM and a 15k drive with 15kRPM.
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Manoj_28
Advisor

Re: Mixing drive types in MSA1000

Thanks Uwe,

Anybody has got any whitepaper on this subject?

Regards
Manoj
e4services
Honored Contributor

Re: Mixing drive types in MSA1000

There is no White Paper, it is just a fact of Architecture. The rotational speed, therefore the read/write performance, is beyond the system architecture of the controller. That is, the controller is not responsible, does not manage, is not aware of what happens to the data once it is sent out the port of the controller.
The rotational speed of the drive only effects how faster the actual drive can read and write the data sent and received from the controller.
In terms of saving data, a faster drive could write more data/second, sending a ready to the controller more qiuckly. But in terms of total system performance, it will depend on the controllers ability to process the data to be sent. It may be, say in the case of a 642, no noticable difference would be seen in 10K vs 15K, since the 642 is so slow in writing data to the disk subsystem.
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Manoj_28
Advisor

Re: Mixing drive types in MSA1000

Thanks E4
Manoj_28
Advisor

Re: Mixing drive types in MSA1000

I am closing this thread

Regards
Manoj