High CPU usage on ZFS

[mailinglists]

Hi,

I did a few benchmarks on latest PM 6 with ZFS.
I wonder why does a simple dd write inside KVM VM or on host eat 20% of E5-2690v2 CPU?

        NAME                                                     STATE     READ WRITE CKSUM
        rpool                                                    ONLINE       0     0     0
          mirror-0                                               ONLINE       0     0     0
            ata-SAMSUNG_MZ7LM960HCHP-000MV_S2LBNXAH324668-part3  ONLINE       0     0     0
            ata-SAMSUNG_MZ7LM960HCHP-000MV_S2LBNXAH324365-part3  ONLINE       0     0     0
          mirror-1                                               ONLINE       0     0     0
            ata-SAMSUNG_MZ7LM960HCHP-000MV_S2LBNXAH324419        ONLINE       0     0     0
            ata-SAMSUNG_MZ7LM960HCHP-000MV_S2LBNXAH324096        ONLINE       0     0     0
          mirror-2                                               ONLINE       0     0     0
            ata-SAMSUNG_MZ7LM960HCHP-000MV_S2LBNXAH324415        ONLINE       0     0     0
            ata-SAMSUNG_MZ7LM960HCHP-000MV_S2LBNXAH324414        ONLINE       0     0     0
        logs
          nvme-INTEL_SSDPE21K100GA_PHKE831500DJ100EGN-part1      ONLINE       0     0     0

What options (besides the removing compression) do we have to reduce CPU usage?

 

[ertanerbek]

ZVOL make that and not caused from compress... This is my personel suggestion, use LVM .

 

[mailinglists]

I need live migration, so lvm is not an option. :-/

 

[ertanerbek]

I need live migration, so lvm is not an option. :-/

Try CEPH

 

[ness1602]

Live migrations also works on lvm-thin

 

[mailinglists]

Hi guys.

all your suggestions are nice.
However live migration with LVM takes forever, because it synces whole VM, but if using ZFS with replication it takes just a few seconds.

However I solved this by installing intel microcode and now host uses much less CPU, or works as expected.
F****g intel and their security flaws.

 

[ness1602]

Yes,LVM migration is slow on gigabit, but it is what it is , if you're stuck with RAID controllers.