ZFS secondarycache option beeing "ignored"

efeu

Renowned Member
Nov 6, 2015
92
10
73
Hi,
I added a cache drive to my pool which has secondarycache=none attribute.

Code:
  pool: spinning
 state: ONLINE
  scan: scrub repaired 0B in 04:40:29 with 0 errors on Sun Oct  9 05:04:31 2022
config:

    NAME                                             STATE     READ WRITE CKSUM
    spinning                                         ONLINE       0     0     0
      raidz1-0                                       ONLINE       0     0     0
        scsi-35000c5008407606f                       ONLINE       0     0     0
        scsi-35000c50083ef05f7                       ONLINE       0     0     0
        scsi-35000c5008407449f                       ONLINE       0     0     0
        scsi-35000cca05821a80c                       ONLINE       0     0     0
    cache
      ata-Samsung_SSD_850_PRO_512GB_S250NXAG930772J  ONLINE       0     0     0
    spares
      sdd                                            AVAIL   

errors: No known data errors

Code:
zfs get -r secondarycache spinning
NAME                                                           PROPERTY        VALUE           SOURCE
spinning                                                       secondarycache  none            local
spinning/backup                                                secondarycache  none            inherited from spinning
spinning/backup/vm-100-disk-0                                  secondarycache  none            inherited from spinning
spinning/backup/vm-100-disk-0@rep_kvm-win_2021-07-15_13:19:14  secondarycache  none            inherited from spinning
spinning/backup/vm-100-disk-1                                  secondarycache  none            inherited from spinning
spinning/backup/vm-100-disk-1@rep_kvm-win_2021-07-15_13:19:14  secondarycache  none            inherited from spinning
spinning/opnsense                                              secondarycache  none            inherited from spinning
spinning/subvol-117-disk-0                                     secondarycache  none            inherited from spinning
spinning/vm-100-disk-0                                         secondarycache  none            inherited from spinning
spinning/vm-100-disk-0@bfnvme                                  secondarycache  none            inherited from spinning
spinning/vm-100-disk-0@next_try                                secondarycache  none            inherited from spinning
spinning/vm-1000-disk-0                                        secondarycache  none            inherited from spinning
spinning/vm-104-disk-0-old                                     secondarycache  none            inherited from spinning
spinning/vm-104-disk-1                                         secondarycache  none            inherited from spinning
spinning/vm-206-disk-0                                         secondarycache  none            inherited from spinning
spinning/vm-207-disk-0                                         secondarycache  none            inherited from spinning

Code:
ZFS Subsystem Report                            Tue Oct 18 10:58:14 2022
Linux 5.15.39-4-pve                                           2.1.5-pve1
Machine: proxmox (x86_64)                                     2.1.5-pve1

L2ARC status:                                                    HEALTHY
        Low memory aborts:                                             0
        Free on write:                                                 0
        R/W clashes:                                                   0
        Bad checksums:                                                 0
        I/O errors:                                                    0

L2ARC size (adaptive):                                           8.6 GiB
        Compressed:                                    87.6 %    7.6 GiB
        Header size:                                    0.0 %    0 Bytes
        MFU allocated size:                            47.6 %    3.6 GiB
        MRU allocated size:                            53.0 %    4.0 GiB
        Prefetch allocated size:                      < 0.1 %    1.2 MiB
        Data (buffer content) allocated size:          97.8 %    7.4 GiB
        Metadata (buffer content) allocated size:       2.8 %  215.4 MiB

L2ARC breakdown:                                                      14
        Hit ratio:                                      0.0 %          0
        Miss ratio:                                   100.0 %         14
        Feeds:                                                      1.2k

L2ARC writes:
        Writes sent:                                    100 %        534

L2ARC evicts:
        Lock retries:                                                  0
        Upon reading:                                                  0

But as you see, "secondarycache=none" is beeing ignored and L2ARC is beeing written/filled.

And no there does not exist any other pool with an l2arc.
 
I can confirm this behavior on:
pve-manager/7.4-3/9002ab8a (running kernel: 5.15.107-2-pve)
zfs-2.1.11-pve1
zfs-kmod-2.1.11-pve1

secondarycache "none" or "metadata" is ignored