Re: HAMMER: you can mount_hammer a UFS that was a hammer fs before

[Bill Hacker <wbh@xxxxxxxxxxxxx>]

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....

;-)

Bill



> 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)