[ovirt-users] Re: export very slow

Thu, 06 Feb 2025 04:51:34 -0800 

Dear Sandro dear all
if I understand correctly, the sequence for backing up a VM in oVirt environment is as follows: 
    1    A snapshot is created (data domain Fibre Channel).
    2    A clone based on the snapshot is created (data domain Fibre Channel).     3    The clone is exported from the "data domain Fibre Channel" to the EXPORT Domain (NFS). 


Both step 2 and step 3 are extremely slow, considering that the data 
domain storage is Fibre Channel with

an 8Gbps link and that the NFS server has a 4x1Gbps Ethernet network.


For example, looking at what VDSM server during step two, I see the 
following:



/usr/bin/qemu-img convert -p -t none -T none -f qcow2 
/rhev/data-center/mnt/blockSD/——id——  -O raw -W 
/rhev/data-center/mnt/blockSD/——id——



creating a clone of a VM with 100GB of disk space takes approximately 55 
minutes.



Checking the processes on the same node during step three, I see the 
following:



/usr/bin/qemu-img convert -p -t none -T none -f raw 
/rhev/data-center/mnt/blockSD/——id——  -O raw -o preallocation=falloc 
/rhev/data-center/mnt/infn-vm05.management:_ovirt_vms/—id——


it takes about 25 minutes.


Is it possible to optimize the qemu-img convert process by modifying 
some parameters using the oVirt setup ?
I am currently using oVirt 4.3.10. If I'll make an update 4.5 are there 
any improvements ?


Thanks
Enrico

Il 04/02/25 17:33, Giulio Casella ha scritto:

Correct, usually backups are performed through the snapshots 
mechanism, not cloning the VM. Ovirt implements also other export 
mechanism for backups (for example CBT, changed block tracking) that 
minimize the amount of data to be transfered.


On 04/02/2025 16:00, Enrico Becchetti via Users wrote:

Dear all


What do you think about the VM clone creation which happens very 
slowly even though the domain data is fibre channel ?
with vproect it would be faster because it does not use this 
mechanism to make backups?


Enrico

Il 04/02/25 15:24, Giulio Casella ha scritto:

Same here.

We happily use storware vprotect, performing full backups during the 
weekend and a couple of incremental backups every other day (for 
some VM 4 backups a day), for every VM living in our cluster.



Full backup is quite slow (obviously proportional to VM size), but 
incremental backup is a matter of (few) minutes.



An export domain is not the right choice for backups, I think you 
should look at it as a storage to move around VMs (between 
datacenters) when you need.


HTH,
gc


On 04/02/2025 15:11, Jayme wrote:

I've always found the same personally. You'd be much better off if 
you could implement an incremental backup solution. vProtect is one 
option that might do the job




On Tue, Feb 4, 2025 at 9:44 AM Enrico Becchetti via Users 
<users@ovirt.org <mailto:users@ovirt.org>> wrote:


        Dear all,

    I have an Ovirt cluster with 3 Dell R7525 nodes and about 70 
virtual
    machines. I have been using ovirtbackup (python) for a long 
time to

    save
    the VMs.


    Unfortunately it has always been a very slow process that with 
time and

    the ever-increasing size of the VMs has become unusable.

    The oVirt cluster has two storage domains. "DATA" is a the fibre
    channel
    type (8Gbs) with 18TB and an EXPORT domain NFS  managed by a
    dual-processor server HPE Proliant with 4x1Gbs.


    I'll give you an example. I have a vm with four vdisk for a 
1.8TB and

    these are the steps performed to backup this VM.

    As you will see it takes many hours to get the clone from the 
snapshot

    and then many hours to copy the clone to the NFS storage.
    How can I reduce the time needed to save ?
    Thank you !
    Best Regards
    Enrico

-----------------------------------------------------------------
    Feb 2, 2025, 6:26:47 AM

    Snapshot 'Snapshot for backup script' creation for VM 
'GRAYLOG-9' was

    initiated by admin@internal-authz.
    45
    admin@internal-authz
    infn-vm10.management
    GRAYLOG-9
    Blank
    INFNPG
    DELL
    70bbb81b-ed44-4700-839a-96c1df8daeea
    oVirt
  -----------------------------------------------------------------

    Feb 2, 2025, 6:27:22 AM

    Snapshot 'Snapshot for backup script' creation for VM 
'GRAYLOG-9' has

    been completed.
    68
    admin@internal-authz
    infn-vm10.management
    GRAYLOG-9
    Blank
    INFNPG
    DELL
    70bbb81b-ed44-4700-839a-96c1df8daeea
    oVirt
  -----------------------------------------------------------------

    Feb 2, 2025, 6:27:37 AM

    VM GRAYLOG-9_BCK_020244 creation was initiated by 
admin@internal- authz.

    37
    admin@internal-authz
    GRAYLOG-9_BCK_020244
    Blank
    INFNPG
    DATA_FC_P2050
    DELL
    edde40d9-2a26-4d88-8a02-bd928c1ded4a
    oVirt
  -----------------------------------------------------------------

    Feb 2, 2025, 1:59:30 PM
    VM GRAYLOG-9_BCK_020244 creation has been completed.
    53
    admin@internal-authz
    GRAYLOG-9_BCK_020244
    Blank
    INFNPG
    DATA_FC_P2050
    DELL
    edde40d9-2a26-4d88-8a02-bd928c1ded4a
    oVirt
  -----------------------------------------------------------------

    Feb 2, 2025, 1:59:34 PM

    Snapshot 'Snapshot for backup script' deletion for VM 
'GRAYLOG-9' was

    initiated by admin@internal-authz.
    342
    admin@internal-authz
    infn-vm10.management
    GRAYLOG-9
    Blank
    INFNPG
    DELL
    fcfc6291-a55f-431a-8b4c-87cb8e3615ff
    oVirt
  -----------------------------------------------------------------

    Feb 2, 2025, 2:04:00 PM

    Snapshot 'Snapshot for backup script' deletion for VM 
'GRAYLOG-9' has

    been completed.
    356
    admin@internal-authz
    infn-vm10.management
    GRAYLOG-9
    Blank
    INFNPG
    DELL
    fcfc6291-a55f-431a-8b4c-87cb8e3615ff
    oVirt
  -----------------------------------------------------------------

    Feb 2, 2025, 2:04:08 PM
    Starting export Vm GRAYLOG-9_BCK_020244 to VMS_EXPORT
    1162
    admin@internal-authz
    GRAYLOG-9_BCK_020244
    INFNPG
    VMS_EXPORT
    DELL
    b964e3b3-df13-4b82-8128-00984eea380b
    oVirt
  -----------------------------------------------------------------

    Feb 4, 2025, 5:27:50 AM
    Vm GRAYLOG-9_BCK_020244 was exported successfully to VMS_EXPORT
    1150
    admin@internal-authz
    GRAYLOG-9_BCK_020244
    INFNPG
    VMS_EXPORT
    DELL
    b964e3b3-df13-4b82-8128-00984eea380b
    oVirt
  -----------------------------------------------------------------

    Feb 4, 2025, 5:27:53 AM

    VM GRAYLOG-9_BCK_020244 configuration was updated by 
admin@internal-

    authz.
    35
    admin@internal-authz
    GRAYLOG-9_BCK_020244
    Blank
    INFNPG
    DELL
    44480c68-10ad-4660-bd9b-297043210503
    oVirt
  -----------------------------------------------------------------

    Feb 4, 2025, 5:28:00 AM

    VM GRAYLOG-9_BCK_020244 was successfully removed by 
admin@internal-

    authz.
    113
    admin@internal-authz
    GRAYLOG-9_BCK_020244
    Blank
    INFNPG
    DELL
    d141ad60-6cf8-4e77-b438-26b5481f4256
    oVirt
  -----------------------------------------------------------------
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--
__________________________________________________________________________

Enrico Becchetti                        Servizio di Calcolo e Reti

Istituto Nazionale di Fisica Nucleare - Sezione di Perugia
Via Pascoli,c/o Dipartimento di Fisica  06123 Perugia (ITALY)
Phone:+39 075 5852777                   Mobile: +39 075 9696225
FAX: +39 075 5847296                    Microsoft Teams: becch...@infn.it
Mail: Enrico.Becchetti<at>pg.infn.it      Skype:enrico_becchetti
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