How to Stop XenServer from Mounting /var/log

BRRABill

Correct. Since /var/log is a mount point for you, though, that is not as simple as deleting or renaming. You have to stop it mounting first. Then you can rmdir /var/log. Then you can symlink.

You can fork this if you want.

How exactly does one do that, stop it from mounting?

scottalanmiller

You have to find the configuration file that is causing it to mount. You already posted the contents of /etc/fstab in another thread and it is not listed in there. So we need to know where XS is getting the information from.

BRRABill

Just as a reminder, this is fstab


LABEL=root-qidkls    /         ext3     defaults   1  1
LABEL=swap-qidkls          swap      swap   defaults   0  0
LABEL=logs-qidkls    /var/log         ext3     defaults   0  2
/opt/xensource/packages/iso/XenCenter.iso   /var/xen/xc-install   iso9660   loop,ro   0  0

scottalanmiller

Oh, I thought that you posted it and it wasn't there. Just remove the third line and you are done.

BRRABill

@scottalanmiller

I posted it before I learned about posting with the "```" so it was probably hard to read.

So that is it, eh?

BRRABill

Can I unmount it while the server is running?

AKA ... what should be the process for the whole job?

Stop rsyslog
Copy files from /var/log to the new location
Unmount /var/log
Delete /var/log folder
Symlink /var/log to other storage
Restart rsyslog

Does that sound about right?

BRRABill

Oooh, I think I am getting somewhere!

lrwxrwxrwx  1 root root   64 Jul 11 13:01 log -> /run/sr-mount/cbe8175f-43b3-3a64-cdac-3c1475aa2d01/xenserverlogs

BRRABill

The one thing to note is that in my system, XS7 used my entire array for VM storage. I boot off USB and only have one presented drive (Raid 5 SSD) in the server.

After discussing with @scottalanmiller it was determined it was probably OK to create a directory alongside the .VHD files in SR-Mount and store the logs there.

So far, so good. Nothing has imploded.

scottalanmiller

Other options would be to use LVM to create two logical volumes on that RAID device or use the RAID device's LVM system to do the same.

BRRABill

Can you think of any reason why XS would object to creating a folder in sr-mount?

scottalanmiller

@BRRABill said in How to Stop XenServer from Mounting /var/log:

Can you think of any reason why XS would object to creating a folder in sr-mount?

Yes, if it is scanning that directory for folders believing that the existence of a folder in that location implies something, then yes.

BRRABill

@scottalanmiller said

Yes, if it is scanning that directory for folders believing that the existence of a folder in that location implies something, then yes.

Would it be safer, do you think, to go with your other method of shrinking the volume and adding another volume for the logging?

I mean, I'd like to figure this out not just for me, but for all the people in the future who ML recommends XS on USB to.

scottalanmiller

You've already done it, so I would just check and see how it is working.

BRRABill

@scottalanmiller said

You've already done it, so I would just check and see how it is working.

Seems fine.

I just like to, you know, check.

I figure someone here would know if it's an OK idea or say
NO FOR THE LOVE OF ALL THAT IS GOOD DO NOT DO THAT!!!!

We have other XS users ... what are they doing?

travisdh1

@BRRABill said in How to Stop XenServer from Mounting /var/log:

@scottalanmiller said

You've already done it, so I would just check and see how it is working.

Seems fine.

I just like to, you know, check.

I figure someone here would know if it's an OK idea or say
NO FOR THE LOVE OF ALL THAT IS GOOD DO NOT DO THAT!!!!

We have other XS users ... what are they doing?

Just letting it log to the usb drive for now. Yes, I've got a copy of the current config that gets taken every day should the usb stick croak.

BRRABill

@travisdh1 said

Just letting it log to the usb drive for now. Yes, I've got a copy of the current config that gets taken every day should the usb stick croak.

Out of curiosity, how are you copying the current config?

Cloning the USB? Or making backups through XC/CLI?

BRRABill

So, things did not go so well overnight. (Note this is a test XS not my production box.)

Couple things happened. Not sure if it is a coincidence, or something more sinister.

I could not connect to this XS from either XC or Putty. You could connect through the local console.

The first thing I did, of course, was the check to see if the logging was still working. /var/log was sitting there with big fat red text. Hmmm. So I figured I would check the LV on /run/sr-mount to see when the logs stopped. Except that was no longer mounted there. Uh oh.

I also noticed there seemed to be something wrong with the reporting of the devices.

So, I decided to reboot the server, and hope it came back up. After taking a looooooooooong time to shut down, it did indeed come back up, but the same problem existed. The LV was not attached, and it had no network connectivity.

The LV still appears to be there, but I wonder if something else went wacky with this XS install. I mean, could putting a subfolder in the VM storage directory really cause this much havoc?

BRRABill

I'm leaning towards something wacky, because even if the SR was detached for some reason, why would the networking not work as well?

scottalanmiller

Looks more like a crash than anything. So it is back up and working after the reboot?

BRRABill

@scottalanmiller said

Looks more like a crash than anything. So it is back up and working after the reboot?

The SR is not mounted, and the networking is not working.

So no, not working. Which is why I wonder if the entire thing just went south for some reason.