Op Wed, 23 Aug 2017 10:37:07 +0200, schreef A L: > ---- From: Ulli Horlacher <frams...@rus.uni-stuttgart.de> -- Sent: > 2017-08-23 - 09:18 ---- > >> On Tue 2017-08-22 (22:48), Ulli Horlacher wrote: >> >>> > Assumptions that all Btrfs features such as snapshots are infinitely >>> > scalable at no cost may be optimistic: >>> > >>> > https://btrfs.wiki.kernel.org/index.php/ Gotchas#Having_many_subvolumes_can_be_very_slow >>> >>> "when you do device removes on file systems with a lot of snapshots, >>> it >>> is unbelievably slow ... took nearly a week to move 20GB of FS data >>> from one device to the other using that method" >>> >>> "a balance on 2TB of data that was heavily snapshotted - it took 3 >>> months" >> >> This is a vanilla SLES12 installation: >> >> root@ptm1:~# grep PRETTY_NAME /etc/os-release PRETTY_NAME="SUSE Linux >> Enterprise Server 12 SP1" >> >> root@ptm1:~# btrfs subvolume list / >> ID 257 gen 358277 top level 5 path @ >> ID 258 gen 978361 top level 257 path @/home ID 259 gen 1252501 top >> level 257 path @/opt ID 260 gen 883012 top level 257 path @/srv ID 261 >> gen 1252673 top level 257 path @/tmp ID 262 gen 1252501 top level 257 >> path @/usr/local ID 263 gen 882958 top level 257 path @/var/crash ID >> 264 gen 1252673 top level 257 path @/var/log ID 265 gen 882923 top >> level 257 path @/var/opt ID 266 gen 1252673 top level 257 path >> @/var/spool ID 267 gen 1252668 top level 257 path @/var/tmp ID 270 gen >> 1252668 top level 257 path @/.snapshots ID 452 gen 358277 top level 270 >> path @/.snapshots/127/snapshot ID 453 gen 1252670 top level 270 path >> @/.snapshots/128/snapshot ID 540 gen 368554 top level 270 path >> @/.snapshots/191/snapshot ID 542 gen 419566 top level 270 path >> @/.snapshots/192/snapshot ID 1035 gen 1027889 top level 270 path >> @/.snapshots/539/snapshot ID 1036 gen 1027889 top level 270 path >> @/.snapshots/540/snapshot ID 1045 gen 1048327 top level 270 path >> @/.snapshots/545/snapshot ID 1046 gen 1048327 top level 270 path >> @/.snapshots/546/snapshot ID 1062 gen 1068800 top level 270 path >> @/.snapshots/555/snapshot ID 1063 gen 1068800 top level 270 path >> @/.snapshots/556/snapshot ID 1122 gen 1130369 top level 270 path >> @/.snapshots/595/snapshot ID 1123 gen 1130369 top level 270 path >> @/.snapshots/596/snapshot ID 1124 gen 1171229 top level 270 path >> @/.snapshots/597/snapshot ID 1125 gen 1171229 top level 270 path >> @/.snapshots/598/snapshot ID 1135 gen 1171229 top level 270 path >> @/.snapshots/605/snapshot ID 1136 gen 1171229 top level 270 path >> @/.snapshots/606/snapshot ID 1137 gen 1171229 top level 270 path >> @/.snapshots/607/snapshot ID 1138 gen 1171229 top level 270 path >> @/.snapshots/608/snapshot ID 1139 gen 1171229 top level 270 path >> @/.snapshots/609/snapshot ID 1140 gen 1171229 top level 270 path >> @/.snapshots/610/snapshot ID 1141 gen 1171229 top level 270 path >> @/.snapshots/611/snapshot ID 1142 gen 1171229 top level 270 path >> @/.snapshots/612/snapshot ID 1158 gen 1172970 top level 270 path >> @/.snapshots/613/snapshot ID 1159 gen 1172972 top level 270 path >> @/.snapshots/614/snapshot >> >> Why does SUSE ignore this "not too many subvolumes" warning? > > Using hundreds or thousands of snapshots is probably fine mostly. > perhaps the slow performance is more related to what changed between > them? I have regularly that many snapshots and export many as "Previous > Versions" to Windows clients over Samba without any performance issues. > But my data doesn't change that much. > > I think those comments on the Wiki are a little misleading without > better details to what workloads are affected this way. > Perhaps someone can set up some tests and publish the results? >
We find that typically apt is very slow on a machine with 50 or so snapshots and raid10. Slow as in probably 10x slower as doing the same update on a machine with 'single' and no snapshots. Other operations seem to be the same speed, especially disk benchmarks do not seem to indicate any performance degradation. >> >> -- >> Ullrich Horlacher Server und Virtualisierung Rechenzentrum >> TIK Universitaet Stuttgart E-Mail: >> horlac...@tik.uni-stuttgart.de Allmandring 30a Tel: >> ++49-711-68565868 70569 Stuttgart (Germany) WWW: >> http://www.tik.uni-stuttgart.de/ >> REF:<20170822204811.go14...@rus.uni-stuttgart.de> >> -- >> 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 -- 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
