On Jun 23, 2011, at 12:16 PM, PJ wrote: > I'm sure many are running ext4 FS's in production, but just want to be > re-assured that there are not currently any major issues before > starting a new project that looks like it will be using ext4. > > I've previously been using xfs but the software for this project > requires ext3/ext4. > > I'm always very cautious before jumping onto a new FS, (new in the > sense it is officially supported now) > > Thanks in advance! I've seen some interesting behavior from "df" on an ext4 file system just today, on a fully-patched CentOS 5.6 system. I was running "watch -d -n 1 df -b G" while copying several TB around. One second, "df" would report that 1600 GB were in use. The next, I'd be up to 2500 GB; and then, over 3000 GB. Then it would drop down to 1200 GB and start counting up again. The amount of disk space actually in use as reported by "du" was closer to 600 GB. I should mention, that is just a sample of the observed behavior. It seemed like "df" would start this fluctuation cycle at the correct number, and I would sometimes catch it there; but it would be off by a couple TB before it re-cycled. Is this something anyone else has seen? This was a new 10 TB file system formatted for ext4 directly, rather than formatted as ext3 and converted to ext4. I've also noticed that I seem to lose more disk space to general overhead than I did with ext3. I'm not talking about the space reserved for root - I've set "-m 0" in both cases. I mean that on an 8 GB logical volume, the formatted size would be 7.8 GB under ext3, versus 7.5 GB with ext4. A 16 GB file system in ext3 would be 15 GB in ext4. Does that match expectations? Thanks, James