XenServer NFS Storage Repo in the SMB
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@Dashrender said:
Is XO looking to move the backup to a different storage target?
Well what happens is it takes an initial backup and sends it to the share. Then it takes a snapshot and compares the differences between the original and the snapshot, then it keeps doing that. So if your VM is completely full, you could have two VHDs that are the same size.
Keep in mind this is only with their delta backup. The normal backups don't do this. This is why I wanted to clarify with @olivier because you could potentially run into an issue without realizing it.
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I'm slowly starting to come around to @scottalanmiller's idea of buying only what you need now, except in things like storage. There are some things you have to plan for growth. If you plan for too little growth then you have issues. By adding extra cost to your project now, you can prevent headaches in the (quite possibly near) future, that makes it worth it to the IT team in that we won't have to worry that we're out of space yet again. That cuts down on wasteful spending, and time lost restoring backups as you upgrade your storage.
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@Dashrender It's not! The SR is just here to store a snapshot to make the delta.
But the files are NOT STORED inside any XenServer, but on an external storage (XOA itself or a NFS share). And you can restore the backup even if you lost your whole XenServer infrastructure.
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@olivier said:
@Dashrender It's not! The SR is just here to store a snapshot to make the delta.
But the files are NOT STORED inside any XenServer, but on an external storage (XOA itself or a NFS share). And you can restore the backup even if you lost your whole XenServer infrastructure.
Ok I have to ask real quick. What's the disaster recovery section for?
Never mind, looks like it copies to a diff pool. I should have read the whole thing first.
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@scottalanmiller the reason for scaling up to 22TB would be for the time & space it takes to build the delta which is a Snapshot on the Host, until it gets put onto the NFS Server.
Which would then copy it to an External NAS (and with planning another external device like a USB)
3-2-1 Backup.
Live and 2 copies on different media and one off site.
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@johnhooks To avoid the "re-importing" step that you need with classical backup
Backup:
- exporting somewhere (any filesystem)
- re importing when need (import time)
DR:
- streaming somewhere (another XenServer host)
- ready to start on the target if needed
edit: so it seems similar but it's not for the same use case.
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@olivier is it a reasonable assumption that you'd want to have at least double the capacity that you're using on the Local Xen SR when building the Delta for that process?
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So if you plan for 11TB(used/live data) you'd really want 22TB of local storage on the Xen SR for XO to have enough space to perform its function.
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@DustinB3403 Even classical backup: for a running VM we need to export the snapshot. So if all your VMs are running and you are backuping everything at once, you'll need to double your space usage (at least during the VM export process).
That's why it's important to use thin provisioned storage as possible.
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And sadly that's nothing we can do about it ^^
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@olivier said:
And sadly that's nothing we can do about it ^^
Nothing wrong with that, just making sure that the 'plans' are correct.
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@Dashrender said:
What red herring? If they made a plan, and the plan ended up being wrong, then all you can do is move onto the normal things, as you said, either grow the storage or find ways to use less storage.
The red herring of adding "remote" as if that didn't have the problem and pointing to "what is the LOCAL" isn't enough. But the answer is the same in either case, add more. The implication, the red herring, was this underlying thought that somehow external storage would not run out and local would. But the risk and the solutions are the same.
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@DustinB3403 said:
@scottalanmiller the reason for scaling up to 22TB would be for the time & space it takes to build the delta which is a Snapshot on the Host, until it gets put onto the NFS Server.
Which would then copy it to an External NAS (and with planning another external device like a USB)
3-2-1 Backup.
Live and 2 copies on different media and one off site.
Okay, so that's assuming 11TB of native VMs and 100% deltas and backing up the entire server in a single go to be able to hit that? Do those things happen?
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About thin provisioning in next XenServer version (Dundee):
THIN PROVISIONED BLOCK STORAGE
iSCSI and HBA block storage can now be configured to be thinly provisioned. This is of particular value to those users who provision guest storage with a high water mark expecting that some allocated storage won't be used. With XenServer 6.5 and prior, the storage provider would allocate the entire disk space which could result in a significant reduction in storage utilization which in turn would increase the cost of virtualization. Now block storage repositories can be configured with an initial size and an increment value. Since storage is critical in any virtualization solution, we are very interested in feedback on this functional change.
I have to make some tests on my side.
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@olivier said:
That's why it's important to use thin provisioned storage as possible.
Like local files and/or NFS
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@DustinB3403 said:
@olivier is it a reasonable assumption that you'd want to have at least double the capacity that you're using on the Local Xen SR when building the Delta for that process?
Not generally, no. That's huge. You have to know something about your system, if course, but this is a theoretical limit, not a practical number.
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@scottalanmiller said:
@DustinB3403 said:
@scottalanmiller the reason for scaling up to 22TB would be for the time & space it takes to build the delta which is a Snapshot on the Host, until it gets put onto the NFS Server.
Which would then copy it to an External NAS (and with planning another external device like a USB)
3-2-1 Backup.
Live and 2 copies on different media and one off site.
Okay, so that's assuming 11TB of native VMs and 100% deltas and backing up the entire server in a single go to be able to hit that? Do those things happen?
No, but if I don't plan for it now, when it happens in a years time because of poor decision making I'll be the asshole who didn't plan for stupidity.
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@DustinB3403 said:
@scottalanmiller said:
@DustinB3403 said:
@scottalanmiller the reason for scaling up to 22TB would be for the time & space it takes to build the delta which is a Snapshot on the Host, until it gets put onto the NFS Server.
Which would then copy it to an External NAS (and with planning another external device like a USB)
3-2-1 Backup.
Live and 2 copies on different media and one off site.
Okay, so that's assuming 11TB of native VMs and 100% deltas and backing up the entire server in a single go to be able to hit that? Do those things happen?
No, but if I don't plan for it now, when it happens in a years time because of poor decision making I'll be the asshole who didn't plan for stupidity.
So the thing that you are ACTUALLY planning for is using 16TB of storage for VMs. That's fine, but be transparent about what you are planning for. It's not the backups, it's overrunning the intended storage.
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@scottalanmiller I wasn't trying to be non-transparent.
Just trying to make a point that you need to have enough space for the eventuality of growth, which might change plans.
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@DustinB3403 said:
@scottalanmiller I wasn't trying to be non-transparent.
Just trying to make a point that you need to have enough space for the eventuality of growth, which might change plans.
To make it transparent, you would state it as X storage + Y for backup overhead. Not project 11TB as the growth number, then add another growth number and the backup overhead together.
So in your case, accounting for future unknown growth, you'd have something like 16TB and a reasonable 5TB of space for snaps during the backup process. Which sounds a lot more reasonable.
