[DragonFlyBSD - Bug #2863] HAMMER synch tid is zero

bugtracker-admin at leaf.dragonflybsd.org bugtracker-admin at leaf.dragonflybsd.org
Thu Dec 10 08:39:23 PST 2015

Issue #2863 has been updated by tkusumi.

from a link in comment #4

ressurected# dd if=/dev/zero of=test.img bs=1m count=15000
15000+0 records in
15000+0 records out
15728640000 bytes transferred in 299.641029 secs (52491610 bytes/sec)
ressurected# vnconfig -c vn test.img
ressurected# disklabel64 -w -r /dev/vn4s0 auto
ressurected# disklabel64 -e /dev/vn4s0
ressurected# newfs_hammer -f -L TEST /dev/vn4s0a
Volume 0 DEVICE /dev/vn4s0a     size  14.65GB
initialize freemap volume 0
initializing the undo map (504 MB)
1 volume total size  14.65GB version 6
boot-area-size:       32.00MB
memory-log-size:      32.00MB
undo-buffer-size:    504.00MB
total-pre-allocated:   0.51GB
fsid:                44b3c7ea-9f56-11e5-a636-11feed02b918
NOTE: Please remember that you may have to manually set up a
cron(8) job to prune and reblock the filesystem regularly.
By default, the system automatically runs 'hammer cleanup'
on a nightly basis.  The periodic.conf(5) variable
'daily_clean_hammer_enable' can be unset to disable this.
Also see 'man hammer' and 'man HAMMER' for more information.
WARNING: HAMMER filesystems less than 50GB are not recommended!
You may have to run 'hammer prune-everything' and 'hammer reblock'
quite often, even if using a nohistory mount.
ressurected# mount /dev/vn4s0a /mnt/
ressurected# cd /mnt/
ressurected# touch it
ressurected# hammer snapq .
ressurected# touch seems
ressurected# hammer snapq .
ressurected# touch to\ be\ working
ressurected# hammer snapq .
ressurected# cd
ressurected# umount /mnt/
ressurected# mount /dev/vn4s0a /mnt/
ressurected# cd /mnt/
ressurected# hammer snapq .
ressurected# touch no\ it\ does\ not
ressurected# hammer snapq .
ressurected# hammer snapls .
Snapshots on .  PFS #0
Transaction ID          Timestamp               Note
0x0000000000000000      2015-12-10 19:17:09 MSK -
0x0000000100008020      2015-12-10 19:16:29 MSK -
0x0000000100008080      2015-12-10 19:16:35 MSK -
0x0000000100008120      2015-12-10 19:16:54 MSK -
0x0000000100010220      2015-12-10 19:17:23 MSK -

Bug #2863: HAMMER synch tid is zero

* Author: shamaz
* Status: New
* Priority: Normal
* Assignee: 
* Category: 
* Target version: 
Hello. This appears on DragonFlyBSD 4.2 (and maybe newer) if you try the
following with HAMMER filesystem:

1) Create a new vnode device.
# dd if=/dev/zero of=test.img bs=1m count=15000
# vnconfig -c vn test.img
# disklabel64  -w -r vn4s0 auto
# disklabel64 -e vn4s0
Add a line like "a:      *      0     HAMMER"

2) Create a HAMMER filesystem:
newfs_hammer -f -L TEST /dev/vn4s0a

3) Mount it:
mount /dev/vn4s0a /mnt

4) Try to sync it:
hammer synctid /mnt

You will see zero sync tid (0x0000000000000000). If you try to set some
debug-related sysctls, it will get you no info at all when syncing. Also
hammer pfs-status /mnt will show that sync-end-tid does not increment in
time as it should. I am not sure if it happens with any non-root hammer FS,
or just with those based on vn pseudo disks.

You have received this notification because you have either subscribed to it, or are involved in it.
To change your notification preferences, please click here: http://bugs.dragonflybsd.org/my/account

More information about the Bugs mailing list