Re-starting a gjournal provider

[Anthony Chavez]

I'm moving this discussion to freebsd-questions, which is probably a
more suitable forum (if not freebsd-geom).  I apologize for the
intrusion and the subsequent crosspost.

Anthony Chavez wrote:
> Hello freebsd-fs,
> 
> I'm trying to get gjournal working on a "removable" hard disk.  I use
> the term loosely, because I'm using a very simple eSATA enclosure: an
> AMS Venus DS5 [1].
> 
> If I swap out disks, atacontrol cap ad0 seems sufficient enough to
> detect the new drive: the reported device model, serial number, firmware
> revision, and CHS values change as one would expect.
> 
> My interpretation of [2] section 5.3 and gjournal(8) is that the
> following sequence of commands should ensure me that all write buffers
> have been flushed and bring the system to a point where it is safe to
> remove a disk.
> 
> sync; sync; sync
> gjournal sync
> umount /dev/ad0s1.journal
> gjournal stop ad0s1.journal
> 
> However, once they are executed, /dev/ad0s1.journal disappears and when
> I swap out the disk it doesn't come back.  The only way I've found to
> bring it back is atacontrol detach ata0; atacontrol attach ata0, which
> doesn't seem like a wise thing to do if I have another device on the
> same channel.
> 
> My question is, do I need to issue gjournal stop before I swap disks?
> And if so, is there any way that I can avoid the atacontrol
> detach/attach cycle that would need to take place before any mount is
> attempted so that /dev/ad0s1.journal appears (if in the drive inserted
> at the time does in fact utilize gjournal; I may want to experiment with
> having disks with either gjournal or soft updates)?
> 
> And while I'm on the subject, are the (gjournal) syncs commands
> preceeding umount absolutely necessary in the case of removable media?
> 
> [1] http://www.american-media.com/product/external/ds/ds.html
> 
> [2] http://www.freebsd.org/doc/en/articles/gjournal-desktop/article.html

-- 
Anthony Chavez                                  http://hexadecagram.org/
mailto:acc at hexadecagram.org                    xmpp:acc at hexadecagram.org

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