PBS with NVME storage way too slow? How to optimize?

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Stefan Kittel

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Proxmox Subscriber
Mar 14, 2026
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Hello,
I've installed the current PBS on a dedicated server in a datacenter (OVH).

AMD EPYC 9135 16-Core Processor (1 Socket)
128 GB RAM
2x 1TB NVME SSD mirror for OS/PBS
6x 8TB NVME SSD (Samsung MZWL67T6HBLC-00AW7)
LAN is 25GBit
Installed native from ISO

I created a ZFS with the 6 SSDs with striping and RAIDZ.
I need abount 40 TB of capacity. So I can' use mirror.

https://semiconductor.samsung.com/ssd/datacenter-ssd/pm9d3a/mzwl67t6hblc-00aw7-bw7/
PCIe 5.0x4, 6800 MB/s write, 12000 MB/s read, 2000K IOPS random read

I create Backups from 3 PM VE Servers.
There is a Windows VM with mailstore. There is one disc 5 TB size.
There is no way to use a more parallel approach.

When I verify localy it or restore it I can't get past 800 MB/Sek.
CPU is about 2%
The disc should reach 3 GB/Sek easy

2026-03-14T17:17:10+00:00: verify data0:vm/100707102/2026-03-12T01:03:51Z
2026-03-14T17:17:10+00:00: check qemu-server.conf.blob
2026-03-14T17:17:10+00:00: check drive-tpmstate0-backup.img.fidx
2026-03-14T17:17:10+00:00: verified 0.01/4.00 MiB in 0.00 seconds, speed 9.53/5766.13 MiB/s (0 errors)
2026-03-14T17:17:10+00:00: check drive-scsi2.img.fidx
2026-03-14T17:18:25+00:00: verified 58744.30/59388.00 MiB in 74.76 seconds, speed 785.72/794.33 MiB/s (0 errors)
2026-03-14T17:18:25+00:00: check drive-scsi0.img.fidx

I get 400 MB/Sek with 24 TB HDDs in Raid5.

I know pbs works with many small chunks, for deduplication and these needs to be put togehter again.

What am I doing wrong?
Or what need I to do to increaese restore speed?

I've described it here in german: https://administrator.de/forum/proxmox-pbs-storage-performance-677340.html

Thanks
Stefan
 
Update

If I tune verify, I get 5.1 GBit/s
proxmox-backup-manager datastore update data0 \ --tuning 'default-verification-readers=16,default-verification-workers=32'

So PBS, the hardware and configuration can deliver this speed.
But restore can't?

When I see this from 2023 I ask myself why restore has not been updated as well.
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Thread 'Proxmox VM Restore Speed'

Hi

I know this subject has been brought up a couple of times already. But even then I've never managed to find a solution in all the different discussions.

First I'll explain the Setup.

I have a CEPH Cluster consisting of three nodes and one PBS node.
  • The CEPH Cluster consists of fairly new hardware with fast NVMe based SSD disks.
  • The PBS Node consists of one older generation server consisting of 12x 12 TB SAS disks in a RAID10 Setup with vdev devices set up.

I've done some extensive performance testing from the CEPH Cluster to the PBS node and vice versa. What I've...

Stefan
 
PVE version, as restore is PVE side.
PVE 8.4 require updates to allow "Restoring from Proxmox Backup Server now fetches multiple chunks concurrently in each worker thread.
This can improve the restore performance in setups with fast network connections and disks.
The number of concurrently fetched chunks and worker threads can be customized using environment variables"
 
Hello, PMVE is 9.1.5.
I tried md striping with ext4.
Currently I can restore with about 1.4 Gbyte/Sec.
Better than the 800 MB with zfs striping or zfsraid1, but slower than the 2x25GBit possible.

The discs and lan should deliver 3GByte/Sec.
CPU von PBS is 5%, RAM uses 5 of 128GB, Swap is 84KB.

During Verify I get 6 GByte/Sek.
Backup is up to 3GByte/Sek with 2 PMVEs sending 5TB new data.

iPerf3 shows about 22GBit LAN usable.

Are there any other options than these?
default-verification-readers=16,default-verification-workers=32

Why is there no autotune or benchmark build in?
 
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