ZFS replication without FS freeze

[tubatodd]

I have 2 Proxmox 6.0 nodes with replication setup between the nodes for a single VM. The replication works, but the freeze and thaw of the guest filesystem causes problems with the application running in the VM. It can't handle the brief pause. Is there a way to do the replication withOUT the freeze and thaw steps?

Thanks
Todd

 

[wolfgang]

Hi,

you can turn off the guest agent.

 

[tubatodd]

@wolfgang thank you for your reply. I stumbled on the freeze and thaw settings in the

/etc/sysconfig/qemu-ga

I've set the

FSFREEZE_HOOK_PATHNAME=/dev/null

and blacklisted the freeze and thaw commands. I'm testing how that impacts our app. So far so good.

 

[tubatodd]

I'm still need to stress test the system during replication to make sure it can handle what we expect, but the basic configuration I'm using is this

BLACKLIST_RPC=guest-file-open,guest-file-close,guest-file-read,guest-file-write,guest-file-seek,guest-file-flush,guest-exec,guest-exec-status,guest-fsfreeze-freeze,guest-fsfreeze-thaw
...
...
FSFREEZE_HOOK_PATHNAME=/dev/null

 

[tubatodd]

@wolfgang these settings seem to have helped greatly, but I could use some additional help. I have the ZFS replication set to every minute. While stress testing the systems, we had a replication failure and timeout that lead to a fault in our system. Is this likely because every minute is too frequent under high load or could it be something else?

 

[wolfgang]

The problem is that zfs commands has a low priority.
So if the pool is under load the sync will fail.