Austin S Hemmelgarn posted on Fri, 25 Apr 2014 14:12:17 -0400 as excerpted: > > On 2014-04-25 13:24, Chris Murphy wrote: >> >> On Apr 25, 2014, at 8:57 AM, Steve Leung <[email protected]> wrote: >> >>> Assuming this is something that needs to be fixed, would I be able to >>> fix this by balancing the system chunks? Since the "force" flag is >>> required, does that mean that balancing system chunks is inherently >>> risky or unpleasant? >> >> I don't think force is needed. You'd use btrfs balance start >> -sconvert=raid1 <mountpoint>; or with -sconvert=raid1,soft although >> it's probably a minor distinction for such a small amount of data. > > The kernel won't allow a balance involving system chunks unless you > specify force, as it considers any kind of balance using them to be > dangerous. Given your circumstances, I'd personally say that the safety > provided by RAID1 outweighs the risk of making the FS un-mountable.
To clear this up, FWIW... In a balance, metadata includes system by default. If you go back and look at the committed balance filters patch, the wording on the -s/system chunks option is that it requires -f/force because one would normally handle system as part of metadata, not for any other reason. What it looks like to me is that the original patch in progress may not have had -s/system as a separate filter at all, treating it as -m/metadata, but perhaps someone suggested having -s/system as a separate option too, and the author agreed. But since -m/metadata includes -s/ system by default, and that was the intended way of doing things, -f/force was added as necessary when doing only -s/system, since presumably that was considered an artificial distinction, and handling -s/ system as a part of -m/metadata was considered the more natural method. Which begs the question[1], is there a safety or procedural reason one should prefer handling metadata and system chunks at the same time, perhaps because rewriting the one involves rewriting critical bits of the other anyway, or is it simply that the author considered system a subset of metadata, anyway? That I don't know. But what I do know is that -f/force isn't required with -m/metadata, which includes -s/system by default anyway, so unless there's reason to treat the two differently, just use -m/metadata and let it handle -s/ system as well. =:^) --- [1] Begs the question: Modern more natural/literal majority usage meaning: invites/forces the question, the question becomes so obvious that it's "begging" to be asked, at least in the speaker/author's (my) own head. Yes, I am aware of but generally prefer "assumes and thus can't prove the postulate" or similar wording as an alternate to the translation-accident meaning. If you have some time and are wondering what I'm talking about and/or think I used the term incorrectly, google it (using duck-duck-go or the like if you don't like google's profiling). =:^) -- Duncan - List replies preferred. No HTML msgs. "Every nonfree program has a lord, a master -- and if you use the program, he is your master." Richard Stallman -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
