disk connection and assignment

[dannyfu0929]

I am a HDS and EMC fun, but recently engaged in some projects using NetApp different model filers. I am trying to find some kind of best practice, unfortunately, not able to get some anything consistent, no matter from NetApp or my company internal.

So I decide to find something by asking some basic technical can/cannot questions instead of best practice. I will start my question one by one, and ask next after I get a consistent answer from most people. appreciate your answers.

1. can disks in one loop be assigned to different heads? if yes, what is the pros and cons? if no, why?

[aborzenkov · Accepted solution]

Yes, they can.

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06.02.2013, в 7:00, "Danny Fu" <xdl-communities@communities.netapp.com<mailto:xdl-communities@communities.netapp.com>> написал(а):

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disk connection and assignment

created by Danny Fu<https://communities.netapp.com/people/dannyfu0929> in Products & Solutions - View the full discussion<https://communities.netapp.com/message/99692#99692>

I am a HDS and EMC fun, but recently engaged in some projects using NetApp different model filers. I am trying to find some kind of best practice, unfortunately, not able to get some anything consistent, no matter from NetApp or my company internal.

So I decide to find something by asking some basic technical can/cannot questions instead of best practice. I will start my question one by one, and ask next after I get a consistent answer from most people. appreciate your answers.

1. can disks in one loop be assigned to different heads? if yes, what is the pros and cons? if no, why?

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[dannyfu0929]

Thanks aborzenkov, are there any pros or cons if assign disks in one loop to different heads?

[aborzenkov]

In general, it is recommended to assign whole loop to one controller. This is also prerequisite for automatic disk assignment. In practice loops are often shared, especially in small configurations or due to hardware limits.

So the only practical drawback I can think of is that replacement disks need to be manually assigned.

[dannyfu0929]

Thanks Aborzenkov,

So question 2:

If there are 2 identical shelves (24 disks in each) connected to one loop/stack, e.g., for a FAS2240-2 active/active configuration, if I want to split the 48 disks to the 2 filers evenly, and create one aggr/rg on each filer.

Should I assign all disks in one shelf to one filer, and assign all disks in another shelf to another filer?

OR assign half disks in each shelf to one filer, and another half disks in each shelf to another filer?

What are the pros and cons?

[ralfaro01zero]

Span aggregates between shelfs is possible, but is not something that I personally like to do; if something wrong happens to a shelf cable or a shelf chassis, your aggregate might get corrupted, the cables and the shelf chassis become a single point of failure. RAID-DP can loose 2 disks without problems, but if you loose more than that your aggregate is toast.

I would configure one aggregate for each shelf and distribute them evenly between controllers. Don't distribute them just by disk count, do it thinking on load, distribute the load evenly between controllers.

Cheers.