XenServer NFS Storage Repo in the SMB



  • So from this topic, it is apparent that NFS is a really critical way of setting up your Storage Repos.

    With Xen, and Xen Orchestra alike.

    But how would you go about build an "unIPODed" NFS file system to run your VM's and XO backup target?


  • Service Provider

    @DustinB3403 said:

    So from this topic, it is apparent that NFS is a really critical way of setting up your Storage Repos.

    The important bit there is.... it is better than iSCSI. The rule of thumb has always been NAS over SAN anyway. This is just an example of why.


  • Service Provider

    @DustinB3403 said:

    But how would you go about build an "unIPODed" NFS file system to run your VM's and XO backup target?

    In a cluster. It's identical to how you make any layer highly reliable. So let's use an example.

    You have a SAM-SD NFS storage server running on OpenSuse. To make this highly reliable you need storage replication and you need failover HA clustering. OpenSuse provides all of this out of the box. For storage you would build on the DRBD storage mirroring layer to mirror the storage of the two nodes. This is Network RAID 1. Then you would use HA clustering to look for a heartbeat between the two hosts and failover should one of them die. This allows your storage to stay online without a dependence on any single node.



  • So multiple NFS servers with multiple paths to the Hosts, meaning multiple NICs and ideally independent switches to support the infrastructure.

    Is this really possible to implement in the SMB space where often only a single "closet" exist?

    Multiple host (of SAM-SD) quality would cost a fortune, and is often well outside of what an SMB would be willing to spend in the life of the business on "computer equipment"



  • why aren't you looking at local storage for the VM's and external storage for the backups?



  • And if you go that way, does it really matter, or better said, do you really need highly available backups?



  • Those two things are assuming you're talking about the SMB of course.



  • @Dashrender said:

    why aren't you looking at local storage for the VM's and external storage for the backups?

    That's kind of where this came from. If you do the delta backups in XO it keeps a snapshot of the disk on the storage repository. So if you have limited space and your SR is local, you might not have enough room for all of the disk snapshots.



  • @Dashrender said:

    why aren't you looking at local storage for the VM's and external storage for the backups?

    The trouble with local storage is the amount of space XO takes to create backups, which get stored locally on the XenServer host(s).

    Which if for example you have 8TB of used storage on your Host and you want to create Backups of that host using XO, you really need to ensure you have a large portion of free space on the Storage Repository.


  • Service Provider

    @DustinB3403 said:

    So multiple NFS servers with multiple paths to the Hosts, meaning multiple NICs and ideally independent switches to support the infrastructure.

    Can be connected directly, no need to have switches. That would just add bottlenecks and complication if you did not need the scale.


  • Service Provider

    @DustinB3403 said:

    Is this really possible to implement in the SMB space where often only a single "closet" exist?

    Possible, sure. Practical, no. You'd use local storage in the SMB space. External storage is exclusively for cost savings "at scale."



  • So with that example I gave.

    8TB of used storage, you build your system to have 11TB of total capacity, would you effectively have enough space to keep a weeks worth of Delta's?

    What about a larger capacity system? At what scale does Local Storage become less favorable?


  • Service Provider

    @DustinB3403 said:

    Multiple host (of SAM-SD) quality would cost a fortune, and is often well outside of what an SMB would be willing to spend in the life of the business on "computer equipment"

    But an SMB would not be looking at external storage, so not really an issue. You only look at external storage to save money at scale. So it's an odd thought to think "someone is so small that they can't try to save money." The only benefit to external is cost savings. So if it doesn't save money, it doesn't come up. If it does save money, size isn't a factor.


  • Service Provider

    @johnhooks said:

    @Dashrender said:

    why aren't you looking at local storage for the VM's and external storage for the backups?

    That's kind of where this came from. If you do the delta backups in XO it keeps a snapshot of the disk on the storage repository. So if you have limited space and your SR is local, you might not have enough room for all of the disk snapshots.

    If you have limited space and your SR is remote, how does that improve things?


  • Service Provider

    @DustinB3403 said:

    @Dashrender said:

    why aren't you looking at local storage for the VM's and external storage for the backups?

    The trouble with local storage is the amount of space XO takes to create backups, which get stored locally on the XenServer host(s).

    How is that an issue? Local storage doesn't use some extra space that remote does not.



  • @scottalanmiller said:

    @johnhooks said:

    @Dashrender said:

    why aren't you looking at local storage for the VM's and external storage for the backups?

    That's kind of where this came from. If you do the delta backups in XO it keeps a snapshot of the disk on the storage repository. So if you have limited space and your SR is local, you might not have enough room for all of the disk snapshots.

    If you have limited space and your SR is remote, how does that improve things?

    The question isn't if you have limited space with remote SR.

    The question is "what is reasonable for local storage and when should "I" be looking into remote storage?"


  • Service Provider

    @DustinB3403 said:

    If you have limited space and your SR is remote, how does that improve things?

    The question isn't if you have limited space with remote SR.

    But if you are designing a system and design it with the same amount of storage, you would have the same design decision in either location. If the question is about "what if someone doesn't plan for enough storage" then the answer is "plan for more".


  • Service Provider

    @DustinB3403 said:

    The question is "what is reasonable for local storage and when should "I" be looking into remote storage?"

    http://www.smbitjournal.com/2013/06/when-to-consider-a-san/

    Logic applies to all external storage. You only consider external when the physical scale in number of VM hosts gets so large that having the storage external makes it cheaper than having it local and the cost savings is a worthwhile trade off versus the increase in risk and effort.



  • @scottalanmiller said:

    @DustinB3403 said:

    If you have limited space and your SR is remote, how does that improve things?

    The question isn't if you have limited space with remote SR.

    But if you are designing a system and design it with the same amount of storage, you would have the same design decision in either location. If the question is about "what if someone doesn't plan for enough storage" then the answer is "plan for more".

    "Plan for more...."

    Well that sure is a simple answer.



  • @scottalanmiller said:

    @DustinB3403 said:

    If you have limited space and your SR is remote, how does that improve things?

    The question isn't if you have limited space with remote SR.

    But if you are designing a system and design it with the same amount of storage, you would have the same design decision in either location. If the question is about "what if someone doesn't plan for enough storage" then the answer is "plan for more".

    Isn't this a quote from you?

    Always implement things when you actually need them, never when you just foresee that you need them


  • Service Provider

    @DustinB3403 said:

    "Plan for more...."

    Well that sure is a simple answer.

    It's a pretty simple question when boil it down to what is really being asked. The question is "what to do when we don't plan for enough storage." It's not about local or remote at all, just about not having enough of it. Get more.

    In both cases the things that would make the problem would make it in both places.


  • Service Provider

    @johnhooks said:

    @scottalanmiller said:

    @DustinB3403 said:

    If you have limited space and your SR is remote, how does that improve things?

    The question isn't if you have limited space with remote SR.

    But if you are designing a system and design it with the same amount of storage, you would have the same design decision in either location. If the question is about "what if someone doesn't plan for enough storage" then the answer is "plan for more".

    Isn't this a quote from you?

    Always implement things when you actually need them, never when you just foresee that you need them

    Sure, but don't do it remotely. Implement it in the right place.



  • So then the nagging follow up question is; How do you calculate enough storage space for your Delta backups on your local storage array?



  • @DustinB3403 said:

    So then the nagging follow up question is; How do you calculate enough storage space for your Delta backups on your local storage array?

    A quick answer I guess would be enough to hold two of the VHDs for each VM. But that doesn't take into account whether they are thin provisioned or anything else.

    However, only enough for 2 would exclude the ability for additional manual snapshots if you want to take some (assuming you're going to use all of that).



  • @johnhooks Well we know that XO with Local Storage is a thick provision delta, @olivier answered that himself.



  • @DustinB3403 Local Storage in LVM. Not file based.


  • Service Provider

    @DustinB3403 said:

    @johnhooks Well we know that XO with Local Storage is a thick provision delta, @olivier answered that himself.

    No, only under certain circumstances that break other best practices. Like with most of these kinds of things, it turns into one broken best practice leading to another leading to disaster.



  • @DustinB3403 said:

    @johnhooks Well we know that XO with Local Storage is a thick provision delta, @olivier answered that himself.

    mine by default are thin I believe. Im def not using all of what is provisioned there.

    0_1452542263924_Screenshot 2016-01-11 at 2.56.58 PM.png


  • Service Provider

    Our local was thin too.



  • @DustinB3403 said:

    @scottalanmiller said:

    @DustinB3403 said:

    If you have limited space and your SR is remote, how does that improve things?

    The question isn't if you have limited space with remote SR.

    But if you are designing a system and design it with the same amount of storage, you would have the same design decision in either location. If the question is about "what if someone doesn't plan for enough storage" then the answer is "plan for more".

    "Plan for more...."

    Well that sure is a simple answer.

    LOL - yeah that is kinda a non answer.

    I take you the question to be, we planned for 8 TB with backups fitting in an additional 3 TB, 3 months later we found out that was to small. At the point I'd say you have a new project, which is a growth project, and you work it from that angle.



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