1

I'm using KVM on Debian 10 as host and for now two guests that are Debian 10 as well. The guests are "stuttering" frequently, what I mean by that is that like at least several times an hour a guest becomes unresponsive for like 10 seconds. If I have an SSH session open and I'm typing I can do nothing until the guest spontaneously "unfreezes". It seems like what I typed just before "freeze" is still buffered, because once the guest unfreezes, it all appears in command line.

The host box does not suffer anything like that.

The host is part of active/passive cluster with following configuration:

  1. Two disks are working in RAID-1 setup, two partitions form /dev/md0 for root fs, two bigger partions are joined into /dev/md1 for guest data.
  2. /dev/md1 is used for DRBD device between two cluster hosts. Protocol C for synchronous writes is used between the hosts.
  3. LVM is stacked on top of DRBD device. Guests use raw LVM volumes for disks.
  4. The second host is NOT present, it's not production yet.

I did not really change anything in either KVM host or guest settings if I remember correctly, just used the defaults. Anyway, this is the configuration I have:

Guest domain XML definition:

% cat bind.xml 
<!--
WARNING: THIS IS AN AUTO-GENERATED FILE. CHANGES TO IT ARE LIKELY TO BE
OVERWRITTEN AND LOST. Changes to this xml configuration should be made using:
  virsh edit bind
or other application using the libvirt API.
-->

<domain type='kvm'> <name>bind</name> <uuid>6fc751ea-2ce0-4e69-b098-48b8ea0fc78a</uuid> <metadata> <libosinfo:libosinfo xmlns:libosinfo="http://libosinfo.org/xmlns/libvirt/domain/1.0"> <libosinfo:os id="http://debian.org/debian/10"/> </libosinfo:libosinfo> </metadata> <memory unit='KiB'>1048576</memory> <currentMemory unit='KiB'>1048576</currentMemory> <vcpu placement='static'>1</vcpu> <os> <type arch='x86_64' machine='pc-q35-3.1'>hvm</type> <bootmenu enable='yes'/> </os> <features> <acpi/> <apic/> <vmport state='off'/> </features> <cpu mode='host-model' check='partial'> <model fallback='allow'/> </cpu> <clock offset='utc'> <timer name='rtc' tickpolicy='catchup'/> <timer name='pit' tickpolicy='delay'/> <timer name='hpet' present='no'/> </clock> <on_poweroff>destroy</on_poweroff> <on_reboot>restart</on_reboot> <on_crash>destroy</on_crash> <pm> <suspend-to-mem enabled='no'/> <suspend-to-disk enabled='no'/> </pm> <devices> <emulator>/usr/bin/qemu-system-x86_64</emulator> <disk type='block' device='disk'> <driver name='qemu' type='raw' cache='none' io='native'/> <source dev='/dev/vgr0/bind'/> <target dev='vda' bus='virtio'/> <boot order='2'/> <address type='pci' domain='0x0000' bus='0x04' slot='0x00' function='0x0'/> </disk> <disk type='file' device='cdrom'> <driver name='qemu' type='raw'/> <target dev='sda' bus='sata'/> <readonly/> <boot order='1'/> <address type='drive' controller='0' bus='0' target='0' unit='0'/> </disk> <controller type='usb' index='0' model='qemu-xhci' ports='15'> <address type='pci' domain='0x0000' bus='0x02' slot='0x00' function='0x0'/> </controller> <controller type='sata' index='0'> <address type='pci' domain='0x0000' bus='0x00' slot='0x1f' function='0x2'/> </controller> <controller type='pci' index='0' model='pcie-root'/> <controller type='pci' index='1' model='pcie-root-port'> <model name='pcie-root-port'/> <target chassis='1' port='0x10'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0' multifunction='on'/> </controller> <controller type='pci' index='2' model='pcie-root-port'> <model name='pcie-root-port'/> <target chassis='2' port='0x11'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x1'/> </controller> <controller type='pci' index='3' model='pcie-root-port'> <model name='pcie-root-port'/> <target chassis='3' port='0x12'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x2'/> </controller> <controller type='pci' index='4' model='pcie-root-port'> <model name='pcie-root-port'/> <target chassis='4' port='0x13'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x3'/> </controller> <controller type='pci' index='5' model='pcie-root-port'> <model name='pcie-root-port'/> <target chassis='5' port='0x14'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x4'/> </controller> <controller type='pci' index='6' model='pcie-root-port'> <model name='pcie-root-port'/> <target chassis='6' port='0x15'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x5'/> </controller> <controller type='pci' index='7' model='pcie-root-port'> <model name='pcie-root-port'/> <target chassis='7' port='0x16'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x6'/> </controller> <controller type='virtio-serial' index='0'> <address type='pci' domain='0x0000' bus='0x03' slot='0x00' function='0x0'/> </controller> <interface type='bridge'> <mac address='52:54:00:da:43:59'/> <source bridge='br0'/> <model type='virtio'/> <address type='pci' domain='0x0000' bus='0x01' slot='0x00' function='0x0'/> </interface> <interface type='bridge'> <mac address='52:54:00:25:ea:03'/> <source bridge='br1'/> <model type='virtio'/> <address type='pci' domain='0x0000' bus='0x07' slot='0x00' function='0x0'/> </interface> <serial type='pty'> <target type='isa-serial' port='0'> <model name='isa-serial'/> </target> </serial> <console type='pty'> <target type='serial' port='0'/> </console> <channel type='unix'> <target type='virtio' name='org.qemu.guest_agent.0'/> <address type='virtio-serial' controller='0' bus='0' port='1'/> </channel> <channel type='spicevmc'> <target type='virtio' name='com.redhat.spice.0'/> <address type='virtio-serial' controller='0' bus='0' port='2'/> </channel> <input type='tablet' bus='usb'> <address type='usb' bus='0' port='1'/> </input> <input type='mouse' bus='ps2'/> <input type='keyboard' bus='ps2'/> <graphics type='spice' autoport='yes'> <listen type='address'/> <image compression='off'/> </graphics> <sound model='ich9'> <address type='pci' domain='0x0000' bus='0x00' slot='0x1b' function='0x0'/> </sound> <video> <model type='qxl' ram='65536' vram='65536' vgamem='16384' heads='1' primary='yes'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x0'/> </video> <redirdev bus='usb' type='spicevmc'> <address type='usb' bus='0' port='2'/> </redirdev> <redirdev bus='usb' type='spicevmc'> <address type='usb' bus='0' port='3'/> </redirdev> <memballoon model='virtio'> <address type='pci' domain='0x0000' bus='0x05' slot='0x00' function='0x0'/> </memballoon> <rng model='virtio'> <backend model='random'>/dev/urandom</backend> <address type='pci' domain='0x0000' bus='0x06' slot='0x00' function='0x0'/> </rng> </devices> </domain>

QEMU settings:

% virsh -c qemu:///system capabilities

<capabilities>

<host> <uuid>53f34900-9b09-11e2-98e4-6c3be51bf934</uuid> <cpu> <arch>x86_64</arch> <model>IvyBridge-IBRS</model> <vendor>Intel</vendor> <microcode version='33'/> <topology sockets='1' cores='4' threads='1'/> <feature name='ds'/> <feature name='acpi'/> <feature name='ss'/> <feature name='ht'/> <feature name='tm'/> <feature name='pbe'/> <feature name='dtes64'/> <feature name='monitor'/> <feature name='ds_cpl'/> <feature name='vmx'/> <feature name='smx'/> <feature name='est'/> <feature name='tm2'/> <feature name='xtpr'/> <feature name='pdcm'/> <feature name='pcid'/> <feature name='osxsave'/> <feature name='arat'/> <feature name='md-clear'/> <feature name='stibp'/> <feature name='ssbd'/> <feature name='xsaveopt'/> <feature name='invtsc'/> <pages unit='KiB' size='4'/> <pages unit='KiB' size='2048'/> </cpu> <power_management> <suspend_mem/> </power_management> <iommu support='no'/> <migration_features> <live/> <uri_transports> <uri_transport>tcp</uri_transport> <uri_transport>rdma</uri_transport> </uri_transports> </migration_features> <topology> <cells num='1'> <cell id='0'> <memory unit='KiB'>16298904</memory> <pages unit='KiB' size='4'>4074726</pages> <pages unit='KiB' size='2048'>0</pages> <distances> <sibling id='0' value='10'/> </distances> <cpus num='4'> <cpu id='0' socket_id='0' core_id='0' siblings='0'/> <cpu id='1' socket_id='0' core_id='1' siblings='1'/> <cpu id='2' socket_id='0' core_id='2' siblings='2'/> <cpu id='3' socket_id='0' core_id='3' siblings='3'/> </cpus> </cell> </cells> </topology> <cache> <bank id='0' level='3' type='both' size='6' unit='MiB' cpus='0-3'/> </cache> <secmodel> <model>apparmor</model> <doi>0</doi> </secmodel> <secmodel> <model>dac</model> <doi>0</doi> <baselabel type='kvm'>+64055:+64055</baselabel> <baselabel type='qemu'>+64055:+64055</baselabel> </secmodel> </host>

<guest> <os_type>hvm</os_type> <arch name='i686'> <wordsize>32</wordsize> <emulator>/usr/bin/qemu-system-i386</emulator> <machine maxCpus='255'>pc-i440fx-3.1</machine> <machine canonical='pc-i440fx-3.1' maxCpus='255'>pc</machine> <machine maxCpus='1'>isapc</machine> <machine maxCpus='255'>pc-1.1</machine> <machine maxCpus='255'>pc-1.2</machine> <machine maxCpus='255'>pc-1.3</machine> <machine maxCpus='255'>pc-i440fx-2.8</machine> <machine maxCpus='255'>pc-1.0</machine> <machine maxCpus='255'>pc-i440fx-2.9</machine> <machine maxCpus='255'>pc-i440fx-2.6</machine> <machine maxCpus='255'>pc-i440fx-2.7</machine> <machine maxCpus='128'>xenfv</machine> <machine maxCpus='255'>pc-i440fx-2.3</machine> <machine maxCpus='255'>pc-i440fx-2.4</machine> <machine maxCpus='255'>pc-i440fx-2.5</machine> <machine maxCpus='255'>pc-i440fx-2.1</machine> <machine maxCpus='255'>pc-i440fx-2.2</machine> <machine maxCpus='288'>pc-q35-3.1</machine> <machine canonical='pc-q35-3.1' maxCpus='288'>q35</machine> <machine maxCpus='255'>pc-i440fx-2.0</machine> <machine maxCpus='288'>pc-q35-2.11</machine> <machine maxCpus='288'>pc-q35-2.12</machine> <machine maxCpus='288'>pc-q35-3.0</machine> <machine maxCpus='1'>xenpv</machine> <machine maxCpus='288'>pc-q35-2.10</machine> <machine maxCpus='255'>pc-i440fx-1.7</machine> <machine maxCpus='288'>pc-q35-2.9</machine> <machine maxCpus='255'>pc-0.15</machine> <machine maxCpus='255'>pc-i440fx-1.5</machine> <machine maxCpus='255'>pc-q35-2.7</machine> <machine maxCpus='255'>pc-i440fx-1.6</machine> <machine maxCpus='255'>pc-i440fx-2.11</machine> <machine maxCpus='288'>pc-q35-2.8</machine> <machine maxCpus='255'>pc-0.13</machine> <machine maxCpus='255'>pc-0.14</machine> <machine maxCpus='255'>pc-i440fx-3.0</machine> <machine maxCpus='255'>pc-i440fx-2.12</machine> <machine maxCpus='255'>pc-q35-2.4</machine> <machine maxCpus='255'>pc-q35-2.5</machine> <machine maxCpus='255'>pc-q35-2.6</machine> <machine maxCpus='255'>pc-i440fx-1.4</machine> <machine maxCpus='255'>pc-i440fx-2.10</machine> <machine maxCpus='255'>pc-0.11</machine> <machine maxCpus='255'>pc-0.12</machine> <machine maxCpus='255'>pc-0.10</machine> <domain type='qemu'/> <domain type='kvm'/> </arch> <features> <cpuselection/> <deviceboot/> <disksnapshot default='on' toggle='no'/> <acpi default='on' toggle='yes'/> <apic default='on' toggle='no'/> <pae/> <nonpae/> </features> </guest>

<guest> <os_type>hvm</os_type> <arch name='x86_64'> <wordsize>64</wordsize> <emulator>/usr/bin/qemu-system-x86_64</emulator> <machine maxCpus='255'>pc-i440fx-3.1</machine> <machine canonical='pc-i440fx-3.1' maxCpus='255'>pc</machine> <machine maxCpus='1'>isapc</machine> <machine maxCpus='255'>pc-1.1</machine> <machine maxCpus='255'>pc-1.2</machine> <machine maxCpus='255'>pc-1.3</machine> <machine maxCpus='255'>pc-i440fx-2.8</machine> <machine maxCpus='255'>pc-1.0</machine> <machine maxCpus='255'>pc-i440fx-2.9</machine> <machine maxCpus='255'>pc-i440fx-2.6</machine> <machine maxCpus='255'>pc-i440fx-2.7</machine> <machine maxCpus='128'>xenfv</machine> <machine maxCpus='255'>pc-i440fx-2.3</machine> <machine maxCpus='255'>pc-i440fx-2.4</machine> <machine maxCpus='255'>pc-i440fx-2.5</machine> <machine maxCpus='255'>pc-i440fx-2.1</machine> <machine maxCpus='255'>pc-i440fx-2.2</machine> <machine maxCpus='288'>pc-q35-3.1</machine> <machine canonical='pc-q35-3.1' maxCpus='288'>q35</machine> <machine maxCpus='255'>pc-i440fx-2.0</machine> <machine maxCpus='288'>pc-q35-2.11</machine> <machine maxCpus='288'>pc-q35-2.12</machine> <machine maxCpus='288'>pc-q35-3.0</machine> <machine maxCpus='1'>xenpv</machine> <machine maxCpus='288'>pc-q35-2.10</machine> <machine maxCpus='255'>pc-i440fx-1.7</machine> <machine maxCpus='288'>pc-q35-2.9</machine> <machine maxCpus='255'>pc-0.15</machine> <machine maxCpus='255'>pc-i440fx-1.5</machine> <machine maxCpus='255'>pc-q35-2.7</machine> <machine maxCpus='255'>pc-i440fx-1.6</machine> <machine maxCpus='255'>pc-i440fx-2.11</machine> <machine maxCpus='288'>pc-q35-2.8</machine> <machine maxCpus='255'>pc-0.13</machine> <machine maxCpus='255'>pc-i440fx-2.12</machine> <machine maxCpus='255'>pc-0.14</machine> <machine maxCpus='255'>pc-i440fx-3.0</machine> <machine maxCpus='255'>pc-q35-2.4</machine> <machine maxCpus='255'>pc-q35-2.5</machine> <machine maxCpus='255'>pc-q35-2.6</machine> <machine maxCpus='255'>pc-i440fx-1.4</machine> <machine maxCpus='255'>pc-i440fx-2.10</machine> <machine maxCpus='255'>pc-0.11</machine> <machine maxCpus='255'>pc-0.12</machine> <machine maxCpus='255'>pc-0.10</machine> <domain type='qemu'/> <domain type='kvm'/> </arch> <features> <cpuselection/> <deviceboot/> <disksnapshot default='on' toggle='no'/> <acpi default='on' toggle='yes'/> <apic default='on' toggle='no'/> </features> </guest>

</capabilities>

Hardware:

% lshw
    description: Desktop Computer
    product: HP Compaq Elite 8300 CMT (QV993AV)
    vendor: Hewlett-Packard
    serial: 
    width: 64 bits
    capabilities: smbios-2.7 dmi-2.7 smp vsyscall32
    configuration: administrator_password=disabled boot=normal chassis=desktop family=103C_53307F G=D frontpanel_password=disabled keyboard_password=disabled power-on_password=disabled sku=.. uuid=0049F353-099B-E211-98E4-6C3BE51BF934
  *-core
       description: Motherboard
       product: 3396
       vendor: Hewlett-Packard
       physical id: 0
       serial: ...
     *-firmware
          description: BIOS
          vendor: Hewlett-Packard
          physical id: 0
          version: K01 v02.83
          date: 10/29/2012
          size: 64KiB
          capacity: 16MiB
          capabilities: pci pnp upgrade shadowing cdboot bootselect edd int5printscreen int9keyboard int14serial int17printer acpi usb biosbootspecification netboot uefi
     *-cache:0
          description: L1 cache
          physical id: 4
          slot: CPU Internal L1
          size: 256KiB
          capacity: 256KiB
          capabilities: internal write-through unified
          configuration: level=1
     *-cache:1
          description: L2 cache
          physical id: 5
          slot: CPU Internal L2
          size: 1MiB
          capacity: 1MiB
          capabilities: internal write-through unified
          configuration: level=2
     *-cache:2
          description: L3 cache
          physical id: 6
          slot: CPU Internal L3
          size: 6MiB
          capacity: 6MiB
          capabilities: internal write-back unified
          configuration: level=3
     *-memory
          description: System Memory
          physical id: 7
          slot: System board or motherboard
          size: 16GiB
        *-bank:0
             description: DIMM DDR3 Synchronous 1600 MHz (0.6 ns)
             product: M378B5173EB0-YK0
             vendor: Samsung
             physical id: 0
             serial: 
             slot: DIMM4
             size: 4GiB
             width: 64 bits
             clock: 1600MHz (0.6ns)
        *-bank:1
             description: DIMM DDR3 Synchronous 1600 MHz (0.6 ns)
             product: M378B5173EB0-YK0
             vendor: Samsung
             physical id: 1
             serial: 
             slot: DIMM3
             size: 4GiB
             width: 64 bits
             clock: 1600MHz (0.6ns)
        *-bank:2
             description: DIMM DDR3 Synchronous 1600 MHz (0.6 ns)
             product: M378B5173EB0-YK0
             vendor: Samsung
             physical id: 2
             serial: 
             slot: DIMM2
             size: 4GiB
             width: 64 bits
             clock: 1600MHz (0.6ns)
        *-bank:3
             description: DIMM DDR3 Synchronous 1600 MHz (0.6 ns)
             product: M378B5173EB0-YK0
             vendor: Samsung
             physical id: 3
             serial: 
             slot: DIMM1
             size: 4GiB
             width: 64 bits
             clock: 1600MHz (0.6ns)
     *-cpu
          description: CPU
          product: Intel(R) Core(TM) i5-3470 CPU @ 3.20GHz
          vendor: Intel Corp.
          physical id: e
          bus info: cpu@0
          version: Intel(R) Core(TM) i5-3470 CPU @ 3.20GHz
          slot: Intel(R) Core(TM) i5-3470 CPU @ 3.20GHz
          size: 1637MHz
          capacity: 3800MHz
          width: 64 bits
          clock: 100MHz
          capabilities: lm fpu fpu_exception wp vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx rdtscp x86-64 constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc cpuid aperfmperf pni pclmulqdq dtes64 monitor ds_cpl vmx smx est tm2 ssse3 cx16 xtpr pdcm pcid sse4_1 sse4_2 x2apic popcnt tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm cpuid_fault epb pti ssbd ibrs ibpb stibp tpr_shadow vnmi flexpriority ept vpid fsgsbase smep erms xsaveopt dtherm ida arat pln pts md_clear flush_l1d cpufreq
          configuration: cores=4 enabledcores=4 threads=4
     *-pci
          description: Host bridge
          product: Xeon E3-1200 v2/3rd Gen Core processor DRAM Controller
          vendor: Intel Corporation
          physical id: 100
          bus info: pci@0000:00:00.0
          version: 09
          width: 32 bits
          clock: 33MHz
          configuration: driver=ivb_uncore
          resources: irq:0

...

    *-pci:0
         description: PCI bridge
         product: 7 Series/C216 Chipset Family PCI Express Root Port 1
         vendor: Intel Corporation
         physical id: 1c
         bus info: pci@0000:00:1c.0
         version: c4
         width: 32 bits
         clock: 33MHz
         capabilities: pci pciexpress msi pm normal_decode bus_master cap_list
         configuration: driver=pcieport
         resources: irq:16 ioport:e000(size=4096) memory:f7c00000-f7cfffff
       *-network:0
            description: Ethernet interface
            product: 82571EB Gigabit Ethernet Controller
            vendor: Intel Corporation
            physical id: 0
            bus info: pci@0000:01:00.0
            logical name: enp1s0f0
            version: 06
            serial: 68:05:ca:1a:a1:94
            size: 1Gbit/s
            capacity: 1Gbit/s
            width: 32 bits
            clock: 33MHz
            capabilities: pm msi pciexpress bus_master cap_list rom ethernet physical tp 10bt 10bt-fd 100bt 100bt-fd 1000bt-fd autonegotiation
            configuration: autonegotiation=on broadcast=yes driver=e1000e driverversion=3.2.6-k duplex=full firmware=5.11-2 latency=0 link=yes multicast=yes port=twisted pair speed=1Gbit/s
            resources: irq:29 memory:f7ca0000-f7cbffff memory:f7c80000-f7c9ffff ioport:e020(size=32) memory:f7c60000-f7c7ffff
       *-network:1
            description: Ethernet interface
            product: 82571EB Gigabit Ethernet Controller
            vendor: Intel Corporation
            physical id: 0.1
            bus info: pci@0000:01:00.1
            logical name: enp1s0f1
            version: 06
            serial: 68:05:ca:1a:a1:95
            size: 1Gbit/s
            capacity: 1Gbit/s
            width: 32 bits
            clock: 33MHz
            capabilities: pm msi pciexpress bus_master cap_list rom ethernet physical tp 10bt 10bt-fd 100bt 100bt-fd 1000bt-fd autonegotiation
            configuration: autonegotiation=on broadcast=yes driver=e1000e driverversion=3.2.6-k duplex=full firmware=5.11-2 latency=0 link=yes multicast=yes port=twisted pair speed=1Gbit/s
            resources: irq:31 memory:f7c40000-f7c5ffff memory:f7c20000-f7c3ffff ioport:e000(size=32) memory:f7c00000-f7c1ffff
    *-usb:2
         description: USB controller
         product: 7 Series/C216 Chipset Family USB Enhanced Host Controller #1
         vendor: Intel Corporation
         physical id: 1d
         bus info: pci@0000:00:1d.0
         version: 04
         width: 32 bits
         clock: 33MHz
         capabilities: pm debug ehci bus_master cap_list
         configuration: driver=ehci-pci latency=0
         resources: irq:23 memory:f7d37000-f7d373ff
       *-usbhost
            product: EHCI Host Controller
            vendor: Linux 4.19.0-13-amd64 ehci_hcd
            physical id: 1
            bus info: usb@4
            logical name: usb4
            version: 4.19
            capabilities: usb-2.00
            configuration: driver=hub slots=3 speed=480Mbit/s
          *-usb
               description: USB hub
               product: Integrated Rate Matching Hub
               vendor: Intel Corp.
               physical id: 1
               bus info: usb@4:1
               version: 0.00
               capabilities: usb-2.00
               configuration: driver=hub slots=8 speed=480Mbit/s
    *-pci:1
         description: PCI bridge
         product: 82801 PCI Bridge
         vendor: Intel Corporation
         physical id: 1e
         bus info: pci@0000:00:1e.0
         version: a4
         width: 32 bits
         clock: 33MHz
         capabilities: pci subtractive_decode bus_master cap_list
    *-isa
         description: ISA bridge
         product: Q77 Express Chipset LPC Controller
         vendor: Intel Corporation
         physical id: 1f
         bus info: pci@0000:00:1f.0
         version: 04
         width: 32 bits
         clock: 33MHz
         capabilities: isa bus_master cap_list
         configuration: driver=lpc_ich latency=0
         resources: irq:0
    *-sata
         description: SATA controller
         product: 7 Series/C210 Series Chipset Family 6-port SATA Controller [AHCI mode]
         vendor: Intel Corporation
         physical id: 1f.2
         bus info: pci@0000:00:1f.2
         logical name: scsi0
         logical name: scsi1
         logical name: scsi2
         version: 04
         width: 32 bits
         clock: 66MHz
         capabilities: sata msi pm ahci_1.0 bus_master cap_list emulated
         configuration: driver=ahci latency=0
         resources: irq:28 ioport:f0d0(size=8) ioport:f0c0(size=4) ioport:f0b0(size=8) ioport:f0a0(size=4) ioport:f060(size=32) memory:f7d36000-f7d367ff
       *-disk:0
            description: ATA Disk
            product: TOSHIBA HDWD120
            vendor: Western Digital
            physical id: 0
            bus info: scsi@0:0.0.0
            logical name: /dev/sda
            version: ACF0
            serial: 
            size: 1863GiB (2TB)
            capabilities: partitioned partitioned:dos
            configuration: ansiversion=5 logicalsectorsize=512 sectorsize=4096 signature=4de1036d
          *-volume:0
               description: EXT4 volume
               vendor: Linux
               physical id: 1
               bus info: scsi@0:0.0.0,1
               logical name: /dev/sda1
               logical name: /boot
               version: 1.0
               serial: 340f09ca-7a41-472e-99e2-d72aecd7517f
               size: 285MiB
               capacity: 285MiB
               capabilities: primary bootable journaled extended_attributes large_files huge_files dir_nlink 64bit extents ext4 ext2 initialized
               configuration: created=2020-12-09 19:54:51 filesystem=ext4 lastmountpoint=/boot modified=2020-12-31 21:12:10 mount.fstype=ext4 mount.options=rw,relatime,stripe=4 mounted=2020-12-31 19:21:14 state=mounted
          *-volume:1
               description: Linux raid autodetect partition
               physical id: 2
               bus info: scsi@0:0.0.0,2
               logical name: /dev/sda2
               capacity: 37GiB
               capabilities: primary multi
          *-volume:2
               description: Linux raid autodetect partition
               physical id: 3
               bus info: scsi@0:0.0.0,3
               logical name: /dev/sda3
               capacity: 1825GiB
               capabilities: primary multi
       *-disk:1
            description: ATA Disk
            product: TOSHIBA HDWD120
            vendor: Western Digital
            physical id: 1
            bus info: scsi@1:0.0.0
            logical name: /dev/sdb
            version: ACF0
            serial: 
            size: 1863GiB (2TB)
            capabilities: partitioned partitioned:dos
            configuration: ansiversion=5 logicalsectorsize=512 sectorsize=4096 signature=b3257d2e
          *-volume:0

...

2 Answers2

0

It wasn't DRBD that was to blame, those were host and VM cache and IO modes that were the problem, writethrough in VM settings and others that apparently reduced disk (rw) throughput to a few hundred kilobytes per second, hence syncs were extremely slow. After optimizing those the problem went away.

0

The hypervisor (host) may be memory swapping. The host has only 16GB RAM per your hardware output. *-memory description: System Memory physical id: 7 slot: System board or motherboard size: 16GiB