DragonFly BSD
DragonFly bugs List (threaded) for 2009-10
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Re: HAMMER: you can mount_hammer a UFS that was a hammer fs before

From: Bill Hacker <wbh@xxxxxxxxxxxxx>
Date: Sun, 25 Oct 2009 23:37:16 +0800

Jan Lentfer wrote:
If a partition contains a hammer fs and you newfs it to a UFS you can afterwards still mount it as hammer fs.
You can even still run hammer info and write data on the partition (tried with dd).

? 'dd' does not know or care anything about a fs.

What happens if you not only 'newfs' to UFS, but actually *write* to it AS a r/w UFS mount? (e.g. - not with 'dd').

If hammer fs can 100% recover from that, there is witchcraft afoot....



Redo the following:

atom# newfs_hammer -L pgsql /dev/ad11s2d Volume 0 DEVICE /dev/ad11s2d size 146.48GB initialize freemap volume 0 --------------------------------------------- 1 volume total size 146.48GB version 2 boot-area-size: 64.00MB memory-log-size: 0.50GB undo-buffer-size: 152.00MB total-pre-allocated: 168.00MB fsid: 98d1b558-c09e-11de-81f0-0122685cfb53

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.

atom# newfs /dev/ad11s2d
/dev/ad11s2d: media size 149993.15MB
Warning: Block size and bytes per inode restrict cylinders per group to 89.
Warning: 1748 sector(s) in last cylinder unallocated
/dev/ad11s2d: 307185964 sectors in 74997 cylinders of 1 tracks, 4096 sectors
149993.1MB in 843 cyl groups (89 c/g, 178.00MB/g, 22528 i/g)
super-block backups (for fsck -b #) at:
32, 364576, 729120, 1093664, 1458208, 1822752, 2187296, 2551840, 2916384, 3280928, 3645472, 4010016, 4374560, 4739104, 5103648, 5468192, 5832736, 6197280, [...]

atom# mount_hammer /dev/ad11s2d /mnt

atom# mount
ROOT on / (hammer, local)
devfs on /dev (devfs, local)
/dev/serno/9SF12T4Y.s2a on /boot (ufs, local)
/pfs/@@-1:00001 on /var (null, local)
/pfs/@@-1:00002 on /tmp (null, local)
/pfs/@@-1:00003 on /usr (null, local)
/pfs/@@-1:00004 on /home (null, local)
/pfs/@@-1:00005 on /usr/obj (null, local)
/pfs/@@-1:00006 on /var/crash (null, local)
/pfs/@@-1:00007 on /var/tmp (null, local)
procfs on /proc (procfs, local)
pgsql on /mnt (hammer, local)

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