XenServer 7 Dom0 memory usage
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@JaredBusch said in XenServer 7 Dom0 memory usage:
I would demote and remove the secondary DC. It is a waste of resources.
That's a good point, can't believe that I missed that. Doesn't make any sense to have two on the same box.
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@frodooftheshire said in XenServer 7 Dom0 memory usage:
@JaredBusch Hi Jared,
Thanks for replying. My thinking behind the secondary DC was in case I had to reboot the primary VM, the secondary VM could at least handle DNS/login requests. As far as backup goes, the primary server is running Storagecraft Shadowprotect SPX with 15 minute continuous incrementals that get sent to a BDR box/cloud. SPX runs at a low level of the OS and doesn't know the difference between a physical & virtual machine, so it's able to make great backups.
If you have ShadowProtect, that handles that discussion well.
Obviously, I am working on assumptions of roles and needs of the employees.
Why would you ever want to reboot the DC in the middle of working hours? I mean yeah, you can if QB goes south and such, but then people are already not productive, so who cares about missing a few DNS queries during a reboot? The people are already non productive.
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@frodooftheshire said in XenServer 7 Dom0 memory usage:
Thanks for replying. My thinking behind the secondary DC was in case I had to reboot the primary VM, the secondary VM could at least handle DNS/login requests.
How often do you need to authenticate while a system is rebooting? Reboots normally take seconds to maybe a minute and if QB is your only application, what authetnication is there? Desktops can go for months without AD being up and no one will notice.
DNS is an issue only if you don't use something like Google for your secondary DNS, which I would because if the primary DNS is down you want people to still see the Internet and so you need this regardless if this hardware fails on you.
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@frodooftheshire said in XenServer 7 Dom0 memory usage:
As far as backup goes, the primary server is running Storagecraft Shadowprotect SPX with 15 minute continuous incrementals that get sent to a BDR box/cloud. SPX runs at a low level of the OS and doesn't know the difference between a physical & virtual machine, so it's able to make great backups.
All good there.
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@scottalanmiller said in XenServer 7 Dom0 memory usage:
DNS is an issue only if you don't use something like Google for your secondary DNS, which I would because if the primary DNS is down you want people to still see the Internet and so you need this regardless if this hardware fails on you.
I completely disagree with this. I know it is a common recommendation, but I have seen too many desktops switch to their secondary DNS and then never switch back. Thus breaking their local connectivity after the server has been rebooted.
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@JaredBusch Out of all the users only about 4 people are working off QuickBooks. The rest of the staff utilize an application that runs off the Cloud, so my thinking was - if there ever was an issue with the primary VM, the majority of staff would be able to continue working.
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@JaredBusch said in XenServer 7 Dom0 memory usage:
@scottalanmiller said in XenServer 7 Dom0 memory usage:
DNS is an issue only if you don't use something like Google for your secondary DNS, which I would because if the primary DNS is down you want people to still see the Internet and so you need this regardless if this hardware fails on you.
I completely disagree with this. I know it is a common recommendation, but I have seen too many desktops switch to their secondary DNS and then never switch back. Thus breaking their local connectivity after the server has been rebooted.
Problem there is that if the server goes down, everything goes down (as far as DNS affects it). I've yet to see a machine go to secondary and never go back. But I work with Windows less often than most.
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@frodooftheshire said in XenServer 7 Dom0 memory usage:
@JaredBusch Out of all the users only about 4 people are working off QuickBooks. The rest of the staff utilize an application that runs off the Cloud, so my thinking was - if there ever was an issue with the primary VM, the majority of staff would be able to continue working.
This is solely about DNS, though, right and not about QuickBooks?
Is there even a reason to have AD for QuickBooks, then? -
@scottalanmiller I thought it was against best practices to use outside DNS as a secondary? From what I've read, even though it's the secondary, you can have instances where DNS requests will try to go there first?
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@frodooftheshire said in XenServer 7 Dom0 memory usage:
@scottalanmiller I thought it was against best practices to use outside DNS as a secondary? From what I've read, even though it's the secondary, you can have instances where DNS requests will try to go there first?
It is for the reason stated.
What I personally do in a small business with only a single server is set their router as the secondary and then the router points to the DC first and then google second.
In my case the router is an Ubiquiti ERL and this works perfectly. Your mileage will vary with other routers.
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@scottalanmiller said in XenServer 7 Dom0 memory usage:
@JaredBusch said in XenServer 7 Dom0 memory usage:
@scottalanmiller said in XenServer 7 Dom0 memory usage:
DNS is an issue only if you don't use something like Google for your secondary DNS, which I would because if the primary DNS is down you want people to still see the Internet and so you need this regardless if this hardware fails on you.
I completely disagree with this. I know it is a common recommendation, but I have seen too many desktops switch to their secondary DNS and then never switch back. Thus breaking their local connectivity after the server has been rebooted.
Problem there is that if the server goes down, everything goes down (as far as DNS affects it). I've yet to see a machine go to secondary and never go back. But I work with Windows less often than most.
Yes, that is the common problem, but I have watched it happen too many times over the years. See my previosu post for my modern resolution.
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@JaredBusch said in XenServer 7 Dom0 memory usage:
@frodooftheshire said in XenServer 7 Dom0 memory usage:
@scottalanmiller I thought it was against best practices to use outside DNS as a secondary? From what I've read, even though it's the secondary, you can have instances where DNS requests will try to go there first?
It is for the reason stated.
What I personally do in a small business with only a single server is set their router as the secondary and then the router points to the DC first and then google second.
In my case the router is an Ubiquiti ERL and this works perfectly. Your mileage will vary with other routers.
That makes sense.
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@scottalanmiller said in XenServer 7 Dom0 memory usage:
@frodooftheshire said in XenServer 7 Dom0 memory usage:
@JaredBusch Out of all the users only about 4 people are working off QuickBooks. The rest of the staff utilize an application that runs off the Cloud, so my thinking was - if there ever was an issue with the primary VM, the majority of staff would be able to continue working.
This is solely about DNS, though, right and not about QuickBooks?
Is there even a reason to have AD for QuickBooks, then?I'm not sure I'm following you on your last question. They don't have AD for QuickBooks. They have AD to help manage users/computers/group policy/etc. This company has aprox 20 computers/users.
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@frodooftheshire said in XenServer 7 Dom0 memory usage:
@scottalanmiller said in XenServer 7 Dom0 memory usage:
@frodooftheshire said in XenServer 7 Dom0 memory usage:
@JaredBusch Out of all the users only about 4 people are working off QuickBooks. The rest of the staff utilize an application that runs off the Cloud, so my thinking was - if there ever was an issue with the primary VM, the majority of staff would be able to continue working.
This is solely about DNS, though, right and not about QuickBooks?
Is there even a reason to have AD for QuickBooks, then?I'm not sure I'm following you on your last question. They don't have AD for QuickBooks. They have AD to help manage users/computers/group policy/etc. This company has aprox 20 computers/users.
Right, but his point is that you do not care about a DC being online for those services, only for DNS. Those services generally work without the DC being online because they are cached.
DNS is the only service that is really critical.
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@frodooftheshire said in XenServer 7 Dom0 memory usage:
@scottalanmiller said in XenServer 7 Dom0 memory usage:
@frodooftheshire said in XenServer 7 Dom0 memory usage:
@JaredBusch Out of all the users only about 4 people are working off QuickBooks. The rest of the staff utilize an application that runs off the Cloud, so my thinking was - if there ever was an issue with the primary VM, the majority of staff would be able to continue working.
This is solely about DNS, though, right and not about QuickBooks?
Is there even a reason to have AD for QuickBooks, then?I'm not sure I'm following you on your last question. They don't have AD for QuickBooks. They have AD to help manage users/computers/group policy/etc. This company has aprox 20 computers/users.
THen no need to worry about a failover, if you aren't using it for QB, no one will notice if it is down.
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@JaredBusch I see what you mean. I initially wasn't even planning on having a secondary VM at all. At the last minute I figured in a pinch it could be helpful if for some reason I had to reboot the primary VM during business hours and users were trying to access their cloud services. And if I was going to have DNS on a secondary server I can't think of a reason to not do DC, because then you get the AD integration, and DNS can read/write instead of just read.
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@frodooftheshire said in XenServer 7 Dom0 memory usage:
@JaredBusch I see what you mean. I initially wasn't even planning on having a secondary VM at all. At the last minute I figured in a pinch it could be helpful if for some reason I had to reboot the primary VM during business hours and users were trying to access their cloud services. And if I was going to have DNS on a secondary server I can't think of a reason to not do DC, because then you get the AD integration, and DNS can read/write instead of just read.
Yeah, that is a perfectly valid reasoning. To me that is more overhead than I want to deal with, thus using the router as a secondary.
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Just in case you want to adjust the dom0 memory.
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I agree with @JaredBusch reasoning for not pointing at DC's only in DNS, though his newly proposed solution is pretty cool - assuming the ERL will flip back to the primary as soon as it's available.
As for the secondary DNS server, assuming you have a standard Windows license, it's really kinda six of one, half dozen of another if you should setup a second VM as an additional DC. I see both sides, can't say that one way or the other is really better. I suppose it's a matter of resources.
