Hi, David Sterba Thanks for review.
> -----Original Message----- > From: David Sterba [mailto:dste...@suse.cz] > Sent: Tuesday, October 13, 2015 7:29 PM > To: Zhao Lei <zhao...@cn.fujitsu.com> > Cc: linux-btrfs@vger.kernel.org; c...@fb.com > Subject: Re: [PATCH] btrfs-progs: mkfs: Enable -d dup for single device > > On Tue, Oct 13, 2015 at 06:29:41PM +0800, Zhao Lei wrote: > > Current code don't support dup profile in single device, except it is > > in mixed mode, because following reason: > > 1: In some ssd with deduplication function, it have no effect. > > 2: For a physical device, it the entire disk broken, -d dup can > > not help. > > 3: Half performance comparing with single profile. > > 4: We have a workaround: Create multi-partition in single device, > > and btefs will treat them as multi device. > > While the above makes sense is true, I'm not sure that DUP was disabled for > these reasons. I'm sure that I read a comment from Chris that dup for data is > intentionally disabled because this would lead to corruption, the code for DUP > for metadata would not work for data. And I can't find the comment, but the > doubt is there. So unless I find it or get otherwise convicend that it's ok, > I won't > merge the patch. I hope you understand that. > > What I remember from the comment is that "it's slightly offset that would lead > to corruption". Before this patch, I had done git blame to search why the condition was added, and hadn't found the exact reason. I will queue xfstests(btrfs/generic) at this profile with all mount option for multi-times, to check is something wrong with this. Thanks Zhaolei -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
