Running XenServer from a USB Drive
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@Dashrender said in Running Xen Server from a USB Drive.:
@Ajin said in Running Xen Server from a USB Drive.:
@BRRABill : Will give it a try again with 64 Gig disk.Currently my xen 6.5 is on an HP server Inbuilt HDD. I am planning of upgrading to Xen 7 & and also move it to usb.
The book I'm reading specifically says not to install to USB stick...
Did they give a reason?
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Yeah because the lack of trim support will slow the disk down a lot. And lack or wear leveling.
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@Dashrender said in Running Xen Server from a USB Drive.:
Yeah because the lack of trim support will slow the disk down a lot. And lack or wear leveling.
That makes some weird assumptions..... like that speed is relevant and that you will have writes sent to the USB stick. So based on that reasoning, I think that it is a false recommendation. It's the same as all the recommendations ever... don't run Xen (or anything) from USB unless you make it non-writing. Or at least non-writing for things like logs.
So given that they explained why and it obviously doesn't apply. We can safely take that as a null recommendation.
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@scottalanmiller I Have installed the OS to a Usb stick , and when trying to boot up with it , The usb stick with the os is not being detected, Tried this with multiple machines and usb sticks
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@scottalanmiller : Now something interesting happened, The USB stick got corrupted after multiple testing with the os installation.Getting a new one now
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@Ajin said in Running Xen Server from a USB Drive.:
@scottalanmiller : Now something interesting happened, The USB stick got corrupted after multiple testing with the os installation.Getting a new one now
That's common if you don't have a solid plan for getting the writes to go elsewhere. The logging kills the USB very quickly. You need to be set up for read only or the USB is not even an option.
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USB boot is not for the faint of heart. It's a great idea and I promote it heavily, but with Xen it is an expert only option. You want to really know what you are doing before going that route.
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@Ajin said in Running Xen Server from a USB Drive.:
@scottalanmiller : Now something interesting happened, The USB stick got corrupted after multiple testing with the os installation.Getting a new one now
Common problem with removable flash storage like SD-Cards or USB thumb drives. They often do not feature wear leveling like a modern SSD. The SD card spec does not say a single word about wear leveling for example.
What @scottalanmiller is referring to is that you need some in-depth knowledge about partitioning, filesystems and overall Linux / Unix to create something solid. You would need to redirect logs (rsyslog for example), lock and pid files (ramdisk), /tmp (ramdisk) and a lot more to create a read-only solution that does not kill your flash with little writes. Best would be to implement something like unionfs or squashfs (AFAIK deprecated and replaced by unionfs) where you have a virtual layer between your storage and every write operation. Such a write operation could be mapped to a ramdisk at the filesystem level with unionfs for example.
But even with such a solution, you need to work around some problems. How would you change your configuration for example on a filesystem that is virtually read-only?
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@thwr : Ok so for executing my plan of running XEN fron USB stick needs some more Reading and R&D as mentioned by @scottalanmiller.
So i am holding it back for now as my main priority is to upgrade Xen Server to 7 , just tried to run it from USB .
Need to invest more time for this USB project .As my priority is upgarding Xen Server , concentrating on it now , I will start a new thread for Upgrading Xen and roll back options if any upgrade error happens..
Thanks a lot for all the valuble suggestions and support for this one .
Wil be back in this thread soon.
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@Ajin any reason to keep trying to use the USB and not just use the disks?
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@scottalanmiller : The reason why i thought of going with the USB is that, i had some issues with the previous version of xen server where xapi ,and some other services gave some trouble in connecting to Xen console, xencenter and Xen orchestra. where if i have the os in the USB , i can easily replace the Memory stick if such issues reoccurs again in very less time than working on the whole re-installation and VMS migration. Plus i had read a lot in mangolassi and many other blogs about running these type of virtualisation platforms from portable storage device and thought it would be a best practice to do .
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@scottalanmiller said in Running Xen Server from a USB Drive.:
@Ajin said in Running Xen Server from a USB Drive.:
@scottalanmiller : Now something interesting happened, The USB stick got corrupted after multiple testing with the os installation.Getting a new one now
That's common if you don't have a solid plan for getting the writes to go elsewhere. The logging kills the USB very quickly. You need to be set up for read only or the USB is not even an option.
If by very quickly you mean several months with a small number of VMs, then I agree. I have two VMs and they have run OK with local logging for several months so far.
I'll agree that there are a lot of factors to consider her, how often you're writing to logs being the biggest one. But if you're still in testing and haven't even booted to the XS yet, I doubt logs are what corrupted your install.
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If I was doing it over again from scratch, I'd probably not use USB.
That being said, I have not had any issues thus far.
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@BRRABill said in Running Xen Server from a USB Drive.:
If I was doing it over again from scratch, I'd probably not use USB.
That being said, I have not had any issues thus far.
Are you redirecting logs?
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@BRRABill said in Running Xen Server from a USB Drive.:
If I was doing it over again from scratch, I'd probably not use USB.
That being said, I have not had any issues thus far.
Yeah I wouldn't either.
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@Dashrender : I am in the testing stage only , was checking the possibilities .
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@Dashrender said in Running Xen Server from a USB Drive.:
@BRRABill said in Running Xen Server from a USB Drive.:
If I was doing it over again from scratch, I'd probably not use USB.
That being said, I have not had any issues thus far.
Are you redirecting logs?
Yes.
