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arik010
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R720XD setup for hyper-v core system

Hello, we bought new dell R720XD  12X 4TB 3.5 7200  and 2x 2.5 300GB 15K RPM
1.does the 2 2.5 bays are for purpose of raid1 aray for system and OS ?
i know that if we install the OS on one of the raid 10 arays (together with data and vmdks ) we will get more redundancy but will it significantly  harm perfomance over installing the OS on raid 1 lun consisting of the two 300GB 15k 2.5 drives?

2. what are advatages and disadvantaged between those configuration?
a. 3X raid 10 luns  (4X 4TB disks)
b. 2x  raid 10 luns ( 6X 4TB disks)

Thanks , Arik.

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Moderator
Moderator

Re: R720XD setup for hyper-v core system

Hello Arik

1.does the 2 2.5 bays are for purpose of raid1 aray for system and OS ?

Yes, you can use the 2 internal slots for an OS. Those slots are seen by the controller the same way as the drives directly attached to the backplane.

2. what are advatages and disadvantaged between those configuration?
a. 3X raid 10 luns  (4X 4TB disks)
b. 2x  raid 10 luns ( 6X 4TB disks)

In theory, the more physical disks you spread the data across the higher the possible IOPS since it is spreading the work load across more disks. At the same time, the larger the array the less reliable it gets. The mean time between failures will be higher with configuration 1, but RAID 10 has a very high up-time and both configurations should have very high up-time. The performance benefit of the larger array will depend on the data being written to it and the selected stripe size. That becomes a very in-depth discussion, and you should hire a consultant if you want to maximize the performance of the array.

Thanks

Daniel Mysinger
Dell EMC, Enterprise Engineer

Get support on Twitter @DellCaresPRO

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arik010
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Re: R720XD setup for hyper-v core system

thank you , about the raid 10 we decided to go on 2 raid 10 array of 6X4TB

does it worth to use the 2 x 2.5 bays for hyper v os install or just place everything on the big raid 10 lun?

i really tempted to use those 2 little bays but don't sure if i get any advantages from that.

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Moderator
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Re: R720XD setup for hyper-v core system

does it worth to use the 2 x 2.5 bays for hyper v os install or just place everything on the big raid 10 lun?

It is always a good idea to separate the host OS from the virtual machine database when virtualizing.

Daniel Mysinger
Dell EMC, Enterprise Engineer

Get support on Twitter @DellCaresPRO

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arik010
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Re: R720XD setup for hyper-v core system

thanks but what is the reason to separate ?

if it is for redundancy i think it's better to stay with the raid 10 array same data and also mimimize number of disk to risk.

but if it about performance i will be happy if anyone spill light onto it , does the hyper-v core os will require much iops from it's system disk?

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Moderator
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Re: R720XD setup for hyper-v core system

thanks but what is the reason to separate ?

Performance

Avoid Storing System Files on Drives Used for Hyper-V Storage
Do not store any system files (Pagefile.sys) on drives dedicated to storing virtual machine data.

Daniel Mysinger
Dell EMC, Enterprise Engineer

Get support on Twitter @DellCaresPRO

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arik010
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Re: R720XD setup for hyper-v core system

here Microsoft telling that hyper-v will not even use page file on OS if there is enough available ram on the system.

http://blogs.technet.com/b/mghazai/archive/2011/05/26/what-s-the-story-of-pagefile-size-on-hyper-v-servers.aspx

now i got really confused , everything is ready and i want to place the system into production next week. 

i will call their consulting services to clarify this issue.

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