Andrei Borzenkov - 02.08.18, 12:35: > Отправлено с iPhone > > > 2 авг. 2018 г., в 12:16, Martin Steigerwald <mar...@lichtvoll.de> > > написал(а):> > > Hugo Mills - 01.08.18, 10:56: > >>> On Wed, Aug 01, 2018 at 05:45:15AM +0200, MegaBrutal wrote: > >>> I know it's a decade-old question, but I'd like to hear your > >>> thoughts > >>> of today. By now, I became a heavy BTRFS user. Almost everywhere I > >>> use BTRFS, except in situations when it is obvious there is no > >>> benefit (e.g. /var/log, /boot). At home, all my desktop, laptop > >>> and > >>> server computers are mainly running on BTRFS with only a few file > >>> systems on ext4. I even installed BTRFS in corporate productive > >>> systems (in those cases, the systems were mainly on ext4; but > >>> there > >>> were some specific file systems those exploited BTRFS features). > >>> > >>> But there is still one question that I can't get over: if you > >>> store > >>> a > >>> database (e.g. MySQL), would you prefer having a BTRFS volume > >>> mounted > >>> with nodatacow, or would you just simply use ext4? > >>> > >> Personally, I'd start with btrfs with autodefrag. It has some > >> > >> degree of I/O overhead, but if the database isn't > >> performance-critical and already near the limits of the hardware, > >> it's unlikely to make much difference. Autodefrag should keep the > >> fragmentation down to a minimum. > > > > I read that autodefrag would only help with small databases. > > I wonder if anyone actually > > a) quantified performance impact > b) analyzed the cause > > I work with NetApp for a long time and I can say from first hand > experience that fragmentation had zero impact on OLTP workload. It > did affect backup performance as was expected, but this could be > fixed by periodic reallocation (defragmentation). > > And even that needed quite some time to observe (years) on pretty high > load database with regular backup and replication snapshots. > > If btrfs is so susceptible to fragmentation, what is the reason for > it?
In the end of my original mail I mentioned a blog article that also had some performance graphs. Did you actually read it? Thanks, -- Martin -- 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
