Chris Murphy posted on Mon, 30 Sep 2013 23:26:16 -0600 as excerpted: > The other thing, clearly the OP is surprised it's taking anywhere near > this long. Had he known in advance, he probably would have made a > different choice. I had a longer version that I wrote first, but decided was /too/ long to post as it was. In it I compared the time of seconds to a couple minutes to do a full btrfs balance here, to the time of days I'm seeing reported on-list. That's down to two reasons, AFAIK, the fact that I'm running SSDs, and the fact that I partition things up so that even for my backups on spinning rust, I'm looking at perhaps a couple hours, not days, for a full balance or pre-btrfs, an mdraid (1) return from degraded. The point there was that when a balance or raid rebuild takes seconds, minutes or hours, it's feasible and likely to do it as a test or as part of routine maintenance, before things get as bad as terabytes of over- allocation. As I result, I actually know what my normal balance times look like since I do them reasonably often, something that someone on a system where it's going to take days isn't likely to have the option or luxury of doing. So there's a benefit in if possible partitioning, even if SSDs aren't a current option, or otherwise managing the data scale so maintenance time scales are at very worst on the scale of hours, not days, and preferably at the low end of that range (based on my mdraid days, a practical limit for me is a couple hours, before it's simply too long to do routinely enough to be familiar with the scale times, etc). Of course that can't be done for all use cases, but if it's at all possible, simply managing the scale helps a *LOT*. As I said, the practical wall before things go off the not routinely manageable end for me is about two hours. A pre-deployment test can give one an idea of time scale, and from there... at least I'd have some idea whether it'd take a day or longer, and if it did there was definitely something wrong. Of course if this /is/ part of that pre-deployment testing or even btrfs development testing, as is appropriate at this stage of btrfs development, then points to him for doing that testing and finding there's either something badly wrong or he's simply off the practical end of the size scale before actual deployment. =:^) -- 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 majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
