VM clone high I/O with hardware RAID-10 SSD drives


Jan 9, 2020
When we perform an offline VM clone, we see a very high I/O for 1-2 minutes, which causes other VMs to slow down considerably. Running the latest Proxmox 7.

RAID-10 is using Intel VROC.
SSDs are: Crucial/Micron Micron_1100_MTFDDAK2T0TBN
Intel(R) Xeon(R) CPU E5-2680 v4 dual CPUs
512 GB RAM
ext4 FS

# mdadm --detail /dev/md126     
         Container : /dev/md/imsm0, member 0
        Raid Level : raid10
        Array Size : 3800748032 (3624.68 GiB 3891.97 GB)
     Used Dev Size : 1900374016 (1812.34 GiB 1945.98 GB)
      Raid Devices : 4
     Total Devices : 4

             State : active
    Active Devices : 4
   Working Devices : 4
    Failed Devices : 0
     Spare Devices : 0

            Layout : near=2
        Chunk Size : 64K

Consistency Policy : resync

              UUID : 26873495:bc13463a:68385e30:f5db71ae
    Number   Major   Minor   RaidDevice State
       3       8       32        0      active sync set-A   /dev/sdc
       2       8       48        1      active sync set-B   /dev/sdd
       1       8        0        2      active sync set-A   /dev/sda
       0       8       16        3      active sync set-B   /dev/sdb

Image attached showing I/O load during offline clone. We also see this very high I/O on a snapshot that includes memory.

Just trying to determine if there is an issue with the hardware/RAID, software configuration issue, or if this is expected for clones/snapshots...


  • proxmox_io_clone.png
    87.9 KB · Views: 6


The Proxmox community has been around for many years and offers help and support for Proxmox VE, Proxmox Backup Server, and Proxmox Mail Gateway.
We think our community is one of the best thanks to people like you!

Get your subscription!

The Proxmox team works very hard to make sure you are running the best software and getting stable updates and security enhancements, as well as quick enterprise support. Tens of thousands of happy customers have a Proxmox subscription. Get yours easily in our online shop.

Buy now!