1. Toxik

    Performance: zvol vs. raw files on a dataset

    Hi, while getting some infos about bhyve I stumbled upon this site: https://klarasystems.com/articles/virtualization-showdown-freebsd-bhyve-linux-kvm/ It's actually about comparing bhyve to KVM, but there is another thing: they compare IO performance of VMs installed in a zvol or in a raw file...
  2. G

    ZFS zvol + cache=writeback - unexpected read speed increase?

    Situation: - ZFS on NVME, 1GB/s nvme read speed - ARC (in ram) size about 120GB - fully heated pve-manager/8.1.4 (running kernel: 6.5.13-1-pve) CPU: E5-2683 v4 This CPU has a very poor per-core performance. This leads to: - Windows 10 VM, Virtio-SCSI Single, iothread, 128kb block, cache=none ->...
  3. R

    pfsense VM with UFS leads to overfull vm disk until reboot

    Hello, I recently moved to running pfsense in a VM on pve-manager/8.1.4/ec5affc9e41f1d79 (running kernel: 6.5.11-8-pve). My proxmox storage is zfs, so using virtio block storage for the vm creates a zvol. In pfsense, in order to avoid zfs on zfs, and write amplification, I am using UFS as the...
  4. S

    Structuring shared storage

    My goal is to use shared storage for VMs, including Windows and Ubuntu machines. However, I'm new to storage concepts and haven't been able to make it work. I have a new server running Proxmox 7.4-3. (It is stand-alone at the moment but will eventually be joined to a cluster with two small...
  5. F

    "Move Disk" ZVOL to other zpool, only allocated contents?

    I'm about to replace the HBA card used for my hdd_pool, so I want to temporarily move the ZVOL virtual drives of my VMs from the hdd_pool to the ssd_pool, just to be safe. I tested with one of the smaller virtual drives that's set to look like a 32G drive to the guest OS and has 7.52G actually...
  6. H

    [SOLVED] How to restore VM using thin ZVOLs

    I have a PVE node with some CT & VM on ZFS. The second ones with thin provisioning on ZVOLs. Now I have installed PBS in another computer to learn how to backup my CT/VM. Everything works flawless. The problem it's when I go into PVE GUI -> PBS storage -> Backups -> SomeVMwithBigVirtualDrive ->...
  7. E

    "timeout: no zvol device link" when I try to start a VM

    Every time i try to start this VM after rebooting the PVE host i get TASK ERROR: timeout: no zvol device link for 'vm-205-disk-0' found after 300 sec found. Everything is updated. I have another win10 VM and that one starts without any issue. (Disk is on rpool) I suspect it have something to...
  8. E

    VM won't start after every reboot because "timeout: no zvol device link"

    Every time i try to start this VM after rebooting the PVE host i get TASK ERROR: timeout: no zvol device link for 'vm-205-disk-0' found after 300 sec found. Everything is updated. I have another win10 VM and that one starts without any issue. (Disk is on rpool) I suspect it have something to...
  9. H

    From a VM OS point of view: It's an "standard" FS (like ext4) still COW when residing in a ZVOL on top of a proxmox host with ZFS?

    I thought that it was true, but after reading some answers in this thread now I have doubts. The real reason why I want to know it's because of the full_page_writes parameter in postgresql DB. Setting it to off improves the performance greatly (almost x2) but for non COW FS keeps the DB in a...
  10. G

    IO [iops bw] fair balancing between multiple VM on ZFS ZVOL

    Good day. Is there best practice how to configure fair balancing io requests from multiple VM when block device in zpool 100% loaded? Thank you.
  11. J

    What are the best practices for snapshotting zvol based VMs

    I might not be searching the correct terms, but I haven't really found any information on ways to manage snapshots for VMs running in zvols on ZFS. - Our system runs VMs on a zpool, and I let PVE automatically create a new zvol for each VM. - I have setup zfs-auto-snapshot to take incremental...
  12. J

    Need help mounting a pre-existing zvol

    All - My dedicated NAS server died, and now I'm recovering my ZFS array. I've got everything sorted except for one piece. I had a zvol exposed as an ISCSI share, and had that imported into proxmox as an lvm disk for VM storage. Now, without the ISCSI portion, I can't figure out how to mount...
  13. B

    How to adjust the qcow2 cluster size of existing images to drastically improve I/O performance?

    Hi I've just read this interesting blog article on jrs-s.net (he have a lot of great articles on ZFS by the way) on the topic of qcow2 vs zvol I/O performance. The interesting part was that fine-tuning the qcow2 cluster_size to match the record size ot the underlying zfs dataset could...
  14. S

    FIO Benchmark on the ZVOL. Fast in Proxmox, slow in VM. Same benchmark, same ZVOL

    Hello! Title says it all, but here a details: Host: Proxmox VE 6.3-6 Guest: Ubuntu Server 18.04.2 LTS SSD: ADATA XPG SX8200 Pro 2 TB (two in ZFS mirror) ZVOL: 90GB, thin-provised, sync=disabled Then i benchmarking this ZVOL directly on the Host i get almost maximum performance that this SSD...
  15. G

    ZFS zvol on HDD locks up VM

    Hello, inside the proxmox GUI I've created a 4 member RAID10 HDD ZFS pool (4T SAS HDDs). I placed a VM disk inside this pool and wanted to copy a big repo from a physical machine to the VM (SCSI disk, discard=on,iothread=1,cache=none) source (physical machine): tar -cpf - repo | mbuffer -s...
  16. H

    zvol volblocksize doubts

    Hello everybody, Right now I have a 4TB zvol that is attached to a VM that works as a fileserver over NFS/SAMBA. There are some issues with this zvol configuration (mainly related with volblocksize) and I would like to create a new one with the right config to replace the old one. This zvol is...
  17. Dunuin

    [TUTORIAL] volblocksize nachträglich ändern / zvol verkleinern / Bei Debian-Gast 2 zvols zu einer zvol zusammenführen

    Moin, Ich musste bei allen meinen VMs nachträglich die volblocksize ändern, sowie bei einer Debian-VM die zvols verkleinern und mehrere zvols zu einer einzigen zusammenführen. Dazu habe ich kaum Informationen finden können und es ist mehr sehr schwer gefallen. Als Gedächtnisstütze habe ich mir...
  18. R

    Upgrading from 5.4 -> 6.2 zvol linking fails

    Completed the upgrade from 5.4 to 6.2. After rebooting, attempted to add a new VM. The raw disk image is created successfully, however, the link fails to create: The contents for the zvol.rules is as follows: # Persistent links for zvol # persistent disk links: /dev/zvol/dataset_name # also...
  19. G

    Best Practise: 'VM's running in ZFS file system or 'Directory'

    HI, I'm fairly new to Proxmox and ZFS. As you can see in the screenshot below, I have set up 2x pools named 'storage' and 'vm'. In each pool, I have set up files systems with different configs for each filesystem. In Proxmox my place to store backups is set up just as a directory under the...
  20. H

    move vm disk to zfs disk in zvol

    I want to move a vm disk to a zfs disk in a zvol. How can I do this?


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