Xenserver and Storage
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@jrc said in Xenserver and Storage:
What kind of overhead does this create (ie if I have 6Tb in each server, does that mean I actually only have 3Tb of usable space since I need 2 copies of everything, 1 for each server)?
It's network RAID 1 in a two node case. You lose 50% of capacity. But you would with a normal SAN, too. Everything is the same as a normal SAN. So if you have 6TB on each of two nodes, you get 6TB usable by the cluster.
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@jrc said in Xenserver and Storage:
Then how on earth does that solution scale like they say it does?
Starwind can use as many 2TB chunks as you want on any given node. And it can use as many nodes as Xen supports. Starwind will use everything Xen can throw at it.
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@jrc said in Xenserver and Storage:
Then how on earth does that solution scale like they say it does? That means you have a limit of ~32Tb of attached storage (Xen's 16* attached VHD limit and 2Tb per VHD limit). How does the virtual appliance handle getting beyond that?
You have to work around the 2TB limit in another way, but Starwind will use it regardless of how you get it there. So Starwind definitely does not have that limit. But trying to use Xen's 2TB limit system under it will create limits on the Xen side.
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Remember, we say Xen but these limits are 100% XenServer. If you were on Xen, you'd have none of these limits.
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Would spanning the drives within the guest address this issue as far as the guest cares? At 2TB we're discussing file shares and large databases anyways.
Things that simply need storage, continuous or not when "physically" looking at them. Within the guest OS simply address the limit there. . .
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@scottalanmiller said in Xenserver and Storage:
@jrc said in Xenserver and Storage:
Then how on earth does that solution scale like they say it does? That means you have a limit of ~32Tb of attached storage (Xen's 16* attached VHD limit and 2Tb per VHD limit). How does the virtual appliance handle getting beyond that?
You have to work around the 2TB limit in another way, but Starwind will use it regardless of how you get it there. So Starwind definitely does not have that limit. But trying to use Xen's 2TB limit system under it will create limits on the Xen side.
I'm sorry of this sounds dense, but what??
(And yeah, I realize when We/I say Xen we mean Xenserver and not pure Xen).
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@dustinb3403 said in Xenserver and Storage:
Would spanning the drives within the guest address this issue as far as the guest cares? At 2TB we're discussing file shares and large databases anyways.
Things that simply need storage, continuous or not when "physically" looking at them. Within the guest OS simply address the limit there. . .
That's true. But only to the total limit that XenServer can provide.
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@scottalanmiller said in Xenserver and Storage:
@dustinb3403 said in Xenserver and Storage:
Would spanning the drives within the guest address this issue as far as the guest cares? At 2TB we're discussing file shares and large databases anyways.
Things that simply need storage, continuous or not when "physically" looking at them. Within the guest OS simply address the limit there. . .
That's true. But only to the total limit that XenServer can provide.
Which the limits are listed here.
255 virtual drives per VM (assuming the guest OS can support it). So at the most for a single VM you could have 521,220 TB's worth of space. . .
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@jrc said in Xenserver and Storage:
@scottalanmiller said in Xenserver and Storage:
@jrc said in Xenserver and Storage:
Then how on earth does that solution scale like they say it does? That means you have a limit of ~32Tb of attached storage (Xen's 16* attached VHD limit and 2Tb per VHD limit). How does the virtual appliance handle getting beyond that?
You have to work around the 2TB limit in another way, but Starwind will use it regardless of how you get it there. So Starwind definitely does not have that limit. But trying to use Xen's 2TB limit system under it will create limits on the Xen side.
I'm sorry of this sounds dense, but what??
(And yeah, I realize when We/I say Xen we mean Xenserver and not pure Xen).
Starwind isn't a bottleneck here. If your goal is to scale to huge sizes, Starwind will do it. But Starwind, as a guest on top of Xen, requires you to provide storage to it to use. If you can't provide the storage, Starwind will just wait on you. You asked how Starwind can scale as large as they claim - but that's not what you are really asking about. Starwind is in no way failing to scale, it's XenServer failing to give Starwind enough storage.
Use something other than local disks on XenServer, switch to Xen, KVM, Hyper-V or ESXi and Starwind will scale beyond any useful sizes for those systems. XenServer has an artificially enforced limitation here, that exists only to cripple its local storage capacity, that cannot be easily worked around. But don't think that Starwind is failing to scale, that's not the issue.
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Ok, let me take a step back here.
On the Host you install a VSAN controller VM, you then attach storage to this VM which it will then use as it's VSAN storage space and map that over to the host via iSCSI. Am I correct so far?
Allright, so with Xenserver, the max attached VHDs would be 16, at 2Tb each. And since this VSAN VM is to be used to home all your VMs on the host, you'd need it to have a fair bit of space. So having roughly a 32Tb limit could be a problem. Does this mean you'd need to have a second VSAN VM in that host, therefore upping that limit to 64Tb? And does the VSAN OS handle spanning the data across all 16 VHDs?
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Switching to pure Xen, you lose XAPI which is what makes XenServer useful. Without XAPI tools like Xen Orchestra simply don't exist for the space. At least not to the same extent.
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@jrc said in Xenserver and Storage:
Ok, let me take a step back here.
On the Host you install a VSAN controller VM, you then attach storage to this VM which it will then use as it's VSAN storage space and map that over to the host via iSCSI. Am I correct so far?
Allright, so with Xenserver, the max attached VHDs would be 16, at 2Tb each. And since this VSAN VM is to be used to home all your VMs on the host, you'd need it to have a fair bit of space. So having roughly a 32Tb limit could be a problem. Does this mean you'd need to have a second VSAN VM in that host, therefore upping that limit to 64Tb? And does the VSAN OS handle spanning the data across all 16 VHDs?
Where are you getting your limits from? I literally just posted them and did the math on what you could provide as storage to a single VM.
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@dustinb3403 said in Xenserver and Storage:
@jrc said in Xenserver and Storage:
Ok, let me take a step back here.
On the Host you install a VSAN controller VM, you then attach storage to this VM which it will then use as it's VSAN storage space and map that over to the host via iSCSI. Am I correct so far?
Allright, so with Xenserver, the max attached VHDs would be 16, at 2Tb each. And since this VSAN VM is to be used to home all your VMs on the host, you'd need it to have a fair bit of space. So having roughly a 32Tb limit could be a problem. Does this mean you'd need to have a second VSAN VM in that host, therefore upping that limit to 64Tb? And does the VSAN OS handle spanning the data across all 16 VHDs?
Where are you getting your limits from? I literally just posted them and did the math on what you could provide as storage to a single VM.
Xenserver has a limit of 16 VHDs per VM, I know this from experience and it is buried in their docs. I think the 255 you mention is for pure Xen, which I am not running.
EDIT: Apparently the 16 VHD limit is a Xenserver 6.5 and earlier thing. Xenserver 7 is 255. I need to upgrade to 7....
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Look at this link.
255 disks per VM, with a maximum of 4096 disks per host at the limits. Not 16.
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@jrc said in Xenserver and Storage:
EDIT: Apparently the 16 VHD limit is a Xenserver 6.5 and earlier thing. Xenserver 7 is 255. I need to upgrade to 7....
Yeah you'd better.
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Which means you can have an absolutely insane amount of storage space attached to the VSAN VM, and then pass that out to your other guests.
@scottalanmiller do any single server units support up to 521,220 TB worth of raw space?
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@jrc said in Xenserver and Storage:
@dustinb3403 said in Xenserver and Storage:
@jrc said in Xenserver and Storage:
Ok, let me take a step back here.
On the Host you install a VSAN controller VM, you then attach storage to this VM which it will then use as it's VSAN storage space and map that over to the host via iSCSI. Am I correct so far?
Allright, so with Xenserver, the max attached VHDs would be 16, at 2Tb each. And since this VSAN VM is to be used to home all your VMs on the host, you'd need it to have a fair bit of space. So having roughly a 32Tb limit could be a problem. Does this mean you'd need to have a second VSAN VM in that host, therefore upping that limit to 64Tb? And does the VSAN OS handle spanning the data across all 16 VHDs?
Where are you getting your limits from? I literally just posted them and did the math on what you could provide as storage to a single VM.
Xenserver has a limit of 16 VHDs per VM, I know this from experience and it is buried in their docs. I think the 255 you mention is for pure Xen, which I am not running.
EDIT: Apparently the 16 VHD limit is a Xenserver 6.5 and earlier thing. Xenserver 7 is 255. I need to upgrade to 7....
Ah good, so not perfect, but there is a solution. Made VDIs to one VM is just like small LUNs in the SAN world. Annoying, but fine.
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@dustinb3403 said in Xenserver and Storage:
@scottalanmiller do any single server units support up to 521,220 TB worth of raw space?
With DAS units, maybe. Some things like large Oracle and IBM chassis can have a single server spanning dozens of racks. So... it's theoretically possible.
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@dustinb3403 said in Xenserver and Storage:
@dbeato You can completely skip Windows and use the Linux VSAN controllers.
https://www.starwindsoftware.com/announcing-new-linux-based-starwind-virtual-storage-appliance-video
Any idea on how I can download this? When I try all I can seem to find is the Windows installer.
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@jrc said in Xenserver and Storage:
@dustinb3403 said in Xenserver and Storage:
@dbeato You can completely skip Windows and use the Linux VSAN controllers.
https://www.starwindsoftware.com/announcing-new-linux-based-starwind-virtual-storage-appliance-video
Any idea on how I can download this? When I try all I can seem to find is the Windows installer.
Use the request demo portion here.
Otherwise I'd hit up the folks @StarWind_Software to point you in the right direction.
