A few questions about HAMMER master/slave PFS

Laurent Vivier laurent at lamzi.com
Mon Aug 27 09:08:10 PDT 2018


Hello DFlyers,

I am running DragonFly 5.2.2 as an NFS server with 2x 2TB LUKS-backed HDD's with HAMMER1 v7 as FS in a PFS master/slave mirror-stream setup and it's been working great so far :)

The setup looks like this :

Disk1 -> LUKS -> HAMMER1_2TB -> PFS# 0 (root) 
Disk2 -> LUKS -> HAMMER_SLAVE -> PFS# 0 (root) + PFS 1 (slave to HAMMER1_2TB / PFS# 0)

Now that I am using the system for a little while, I have a few questions regarding its behavior :

1) I realized that the HAMMER slave PFS has several snapshots (not created by me) that seems seemingly impossible to remove e.g

Hikaeme# hammer info /HAMMER_SLAVE
Volume identification
    Label               hammer1_secure_slave
    No. Volumes         1
    HAMMER Volumes      /dev/mapper/knox2
    Root Volume         /dev/mapper/knox2
    FSID                0198767f-7139-11e8-9608-6d626d258b95
    HAMMER Version      7
Big-block information
    Total          238335
    Used           192009 (80.56%)
    Reserved           32 (0.01%)
    Free            46294 (19.42%)
Space information
    No. Inodes      35668
    Total size       1.8T (1999298887680 bytes)
    Used             1.5T (80.56%)
    Reserved         256M (0.01%)
    Free             362G (19.42%)
PFS information
      PFS#  Mode    Snaps
         0  MASTER      0 (root PFS)
         1  SLAVE       3
Hikaeme# hammer snapls /HAMMER_SLAVE/pfs/hanma
Snapshots on /HAMMER_SLAVE/pfs/hanma    PFS#1
Transaction ID        Timestamp        Note
0x00000001034045c0    2018-07-04 18:19:42 CEST    -
0x00000001034406c0    2018-07-09 19:28:04 CEST    -
0x000000010383bc30    2018-08-12 10:51:07 CEST    -
Hikaeme# hammer snaprm 0x00000001034045c0
hammer: hammer snaprm 0x00000001034045c0: Operation not supported

My question here is should I worry about it/is that an intended behavior ? 

2) When executing hammer info and looking at the used space between master and slave PFS, I have quite a big difference (22GB, even after running hammer cleanup)

Hikaeme# hammer info
Volume identification
    Label               HAMMER1_2TB
    No. Volumes         1
    HAMMER Volumes      /dev/mapper/knox
    Root Volume         /dev/mapper/knox
    FSID                81e9d5eb-6be7-11e8-802d-6d626d258b95
    HAMMER Version      7
Big-block information
    Total          238335
    Used           194636 (81.66%)
    Reserved           32 (0.01%)
    Free            43667 (18.32%)
Space information
    No. Inodes      35665
    Total size       1.8T (1999298887680 bytes)
    Used             1.5T (81.66%)
    Reserved         256M (0.01%)
    Free             341G (18.32%)
PFS information
      PFS#  Mode    Snaps
         0  MASTER      0 (root PFS)

Volume identification
    Label               hammer1_secure_slave
    No. Volumes         1
    HAMMER Volumes      /dev/mapper/knox2
    Root Volume         /dev/mapper/knox2
    FSID                0198767f-7139-11e8-9608-6d626d258b95
    HAMMER Version      7
Big-block information
    Total          238335
    Used           191903 (80.52%)
    Reserved           32 (0.01%)
    Free            46400 (19.47%)
Space information
    No. Inodes      35668
    Total size       1.8T (1999298887680 bytes)
    Used             1.5T (80.52%)
    Reserved         256M (0.01%)
    Free             363G (19.47%)
PFS information
      PFS#  Mode    Snaps
         0  MASTER      0 (root PFS)
         1  SLAVE       3

Is that something I should be worried about too ? As far as I can tell the replication of new files from master and slave works great, I can see the new files on the slave PFS fairly quickly.

Wishing you all a good day,

Laurent

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