On Sun, Jun 15, 2014 at 11:45:37PM +0200, Martin Steigerwald wrote: > Am Samstag, 14. Juni 2014, 12:59:31 schrieb Kai Krakow: > > Well, how did I accomblish that? > > Setting no cow and defragmenting regularily? > > Quite a complex setup for a casual Linux user. > > Any solution should be automatic. I´d suggest by a combination of sane > application behaviour and measures within the filesystem. > > > First, I've set the journal directories nocow. Of course, systemd should do > > this by default. I'm not sure if this is a packaging or systemd code issue, > > tho. But I think the systemd devs are in common that for cow fs, the > > journal directories should be set nocow. After all, the journal is a > > transactional database - it does not need cow protection at all costs. And > > I think they have their own checksumming protection. So, why let systemd > > bother with that? A lot of other software has the same semantic problems > > with btrfs, too (ex. MySQL) where nobody shouts at the "inabilities" of the > > programmers. So why for systemd? Just because it's intrusive by its nature > > for being a radically and newly designed init system and thus requires some > > learning by its users/admins/packagers? Really? Come on... As admin and/or > > packager you have to stay with current technologies and developments > > anyways. It's only important to hide the details from the users. > > But nocow also disables the possibilty to snapshot these files, AFAIK.
No, it's the other way around: snapshots break the nodatacow behaviour. With nodatacow set, taking a snapshot will allow exactly one CoW operation on the file data (preserving the original extent for the snapshot to use), and then revert to nodatacow on the newly-written extent. So fragmentation will still occur, after every snapshot. Ideally, we'd use proper CoW rather than the RoW (redirect on write) that we actually use, so that the _original_ is maintained without fragmentation, and the copy fragments, but the performance for that sucks (it uses twice the write bandwidth). Hugo. > Akonadi > does this for its database directory as well for new install. But I am not > completely happy with that approach. > > And well I would say that the following differing results are caused by > specific application behavior – my bet would be rsyslog sequentially > appending to the file while systemd used the journal files more than a > database, databases fragment heavily on BTRFS due to COW: > > > merkaba:/var/log/journal/1354039e4d4bb8de4f97ac8400000004> filefrag * > system@0004e2025580f3c5-c625739d3033b738.journal~: 1 extent found > system@0004f94fbee5f4d1-1cfb9bed12a79bde.journal~: 2771 extents found > system@0004f98240efba02-b465b39a7ed0bdbe.journal~: 2534 extents found > system@0004f9ff739ad927-4650a2ca62bf9378.journal~: 4951 extents found > system@0004fa17feb65603-a7597828f9823e38.journal~: 1244 extents found > system@0004fa3f0e96b653-d6f9d5795c9ef869.journal~: 1419 extents found > system@0004fa4c448b8a95-c95a3b7950fd704d.journal~: 1511 extents found > system@0004fa5dddb554e0-33c319ebb5f8100f.journal~: 1729 extents found > system@0004fad81852c750-20a36082c6006c8a.journal~: 10257 extents found > system@0004fad970b56567-44bf4a94314792fc.journal~: 932 extents found > system@0004fb128307b981-7f2104da8b2c9fb2.journal~: 6757 extents found > system@0004fb1c3eef86c3-8adbea51a1c98729.journal~: 1498 extents found > system@0004fb1c419fb301-7303f7fd9165ed26.journal~: 19 extents found > system@0004fb44feafbafd-b7433e90b1d3d718.journal~: 2265 extents found > system@0004fb6ddf63e4d3-b40e8f4701670bff.journal~: 1894 extents found > system@0004fb6e412c3f7e-3890be9c2119a7bb.journal~: 1038 extents found > system@54803afb1b1d42b387822c56e61bc168-000000000002b364-0004e1c4aabbeefa.journal: > 2 extents found > system@54803afb1b1d42b387822c56e61bc168-000000000002b365-0004e1c4ab5b0246.journal: > 1 extent found > system@bd18e6867b824ba7b572de31531218a9-0000000000000001-0004e202555a0493.journal: > 3232 extents found > system.journal: 3855 extents found > user-1000@0004e202588086cf-3d4130a580b63101.journal~: 1 extent found > user-1000@0004f9ff74415375-6b5dd1c3d76b09ce.journal~: 1046 extents found > user-1000@0004fa17ff12ef0c-34297fcc8c06dd4b.journal~: 96 extents found > user-1000@0004fa3f0eee8e41-dfb1f54bd31e4967.journal~: 84 extents found > user-1000@0004fa4c475a0a63-d8badb620094bce8.journal~: 173 extents found > user-1000@0004fa5de0c650e0-522069bac82c754e.journal~: 319 extents found > user-1000@0004fad818a7a980-593b8f3971b2e697.journal~: 2465 extents found > user-1000@0004fad97160c3ad-552b27f891e7a24e.journal~: 106 extents found > user-1000@0004fb1283616e7e-1fbca0bef31bd92b.journal~: 283 extents found > user-1000@0004fb6de033b269-018b4cbc2b1f319b.journal~: 874 extents found > user-1000@bd18e6867b824ba7b572de31531218a9-00000000000007c7-0004e2025881a1ee.journal: > 293 extents found > user-1000.journal: 4663 extents found > user-120.journal: 5 extents found > user-2012@0004fa4c02142cad-f97563ed0105bfb3.journal~: 749 extents found > user-2012@0004fa4d8255b2df-43248028d422ca78.journal~: 29 extents found > user-2012@0004fa5de40372db-d1f3c6428ddeec22.journal~: 122 extents found > user-2012@0004fad81b8cd9d8-ed2861a9fa1b163c.journal~: 575 extents found > user-2012@0004fad980139d4e-94ad07f4a8fae3cc.journal~: 25 extents found > user-2012@0004fb160f2d5334-99462eb429f4cb7b.journal~: 416 extents found > user-2012@54803afb1b1d42b387822c56e61bc168-0000000000011c75-0004ddb2be06d876.journal: > 2 extents found > user-2012.journal: 453 extents found > user-65534@0004fa4c62bf4a71-6b4c53dfc06dd588.journal~: 46 extents found > user-65534.journal: 91 extents found > merkaba:/var/log/journal/1354039e4d4bb8de4f97ac8400000004> cd .. > merkaba:/var/log/journal> cd .. > > > > > merkaba:/var/log/journal/1354039e4d4bb8de4f97ac8400000004> ls -lh > insgesamt 495M > -rw-r-----+ 1 root root 6,8M Jul 21 2013 > system@0004e2025580f3c5-c625739d3033b738.journal~ > -rw-r-----+ 1 root systemd-journal 14M Mai 14 00:40 > system@0004f94fbee5f4d1-1cfb9bed12a79bde.journal~ > -rw-r-----+ 1 root systemd-journal 14M Mai 16 12:55 > system@0004f98240efba02-b465b39a7ed0bdbe.journal~ > -rw-r-----+ 1 root systemd-journal 26M Mai 22 18:17 > system@0004f9ff739ad927-4650a2ca62bf9378.journal~ > -rw-r-----+ 1 root systemd-journal 6,3M Mai 23 23:34 > system@0004fa17feb65603-a7597828f9823e38.journal~ > -rw-r-----+ 1 root systemd-journal 6,6M Mai 25 22:10 > system@0004fa3f0e96b653-d6f9d5795c9ef869.journal~ > -rw-r-----+ 1 root systemd-journal 7,7M Mai 26 13:56 > system@0004fa4c448b8a95-c95a3b7950fd704d.journal~ > -rw-r-----+ 1 root systemd-journal 9,7M Mai 27 10:56 > system@0004fa5dddb554e0-33c319ebb5f8100f.journal~ > -rw-r-----+ 1 root systemd-journal 50M Jun 2 12:45 > system@0004fad81852c750-20a36082c6006c8a.journal~ > -rw-r-----+ 1 root systemd-journal 5,2M Jun 2 14:21 > system@0004fad970b56567-44bf4a94314792fc.journal~ > -rw-r-----+ 1 root systemd-journal 34M Jun 5 10:27 > system@0004fb128307b981-7f2104da8b2c9fb2.journal~ > -rw-r-----+ 1 root systemd-journal 8,4M Jun 5 22:03 > system@0004fb1c3eef86c3-8adbea51a1c98729.journal~ > -rw-r-----+ 1 root systemd-journal 3,7M Jun 5 22:04 > system@0004fb1c419fb301-7303f7fd9165ed26.journal~ > -rw-r-----+ 1 root systemd-journal 12M Jun 7 22:40 > system@0004fb44feafbafd-b7433e90b1d3d718.journal~ > -rw-r-----+ 1 root systemd-journal 11M Jun 9 23:27 > system@0004fb6ddf63e4d3-b40e8f4701670bff.journal~ > -rw-r-----+ 1 root systemd-journal 6,3M Jun 9 23:54 > system@0004fb6e412c3f7e-3890be9c2119a7bb.journal~ > -rw-r-----+ 1 root adm 128M Jul 18 2013 > system@54803afb1b1d42b387822c56e61bc168-000000000002b364-0004e1c4aabbeefa.journal > -rw-r-----+ 1 root root 7,4M Jul 20 2013 > system@54803afb1b1d42b387822c56e61bc168-000000000002b365-0004e1c4ab5b0246.journal > -rw-r-----+ 1 root systemd-journal 23M Mai 11 10:21 > system@bd18e6867b824ba7b572de31531218a9-0000000000000001-0004e202555a0493.journal > -rw-r-----+ 1 root systemd-journal 19M Jun 15 23:37 system.journal > -rw-r-----+ 1 root root 3,6M Jul 21 2013 > user-1000@0004e202588086cf-3d4130a580b63101.journal~ > -rw-r-----+ 1 root systemd-journal 4,8M Mai 22 18:17 > user-1000@0004f9ff74415375-6b5dd1c3d76b09ce.journal~ > -rw-r-----+ 1 root systemd-journal 3,6M Mai 23 23:34 > user-1000@0004fa17ff12ef0c-34297fcc8c06dd4b.journal~ > -rw-r-----+ 1 root systemd-journal 3,6M Mai 25 22:10 > user-1000@0004fa3f0eee8e41-dfb1f54bd31e4967.journal~ > -rw-r-----+ 1 root systemd-journal 3,7M Mai 26 13:57 > user-1000@0004fa4c475a0a63-d8badb620094bce8.journal~ > -rw-r-----+ 1 root systemd-journal 3,7M Mai 27 10:56 > user-1000@0004fa5de0c650e0-522069bac82c754e.journal~ > -rw-r-----+ 1 root systemd-journal 15M Jun 2 12:45 > user-1000@0004fad818a7a980-593b8f3971b2e697.journal~ > -rw-r-----+ 1 root systemd-journal 3,6M Jun 2 14:22 > user-1000@0004fad97160c3ad-552b27f891e7a24e.journal~ > -rw-r-----+ 1 root systemd-journal 3,7M Jun 5 10:27 > user-1000@0004fb1283616e7e-1fbca0bef31bd92b.journal~ > -rw-r-----+ 1 root systemd-journal 5,2M Jun 9 23:27 > user-1000@0004fb6de033b269-018b4cbc2b1f319b.journal~ > -rw-r-----+ 1 root systemd-journal 3,8M Mai 11 10:21 > user-1000@bd18e6867b824ba7b572de31531218a9-00000000000007c7-0004e2025881a1ee.journal > -rw-r-----+ 1 root systemd-journal 35M Jun 15 23:38 user-1000.journal > -rw-r-----+ 1 root systemd-journal 3,6M Apr 28 09:52 user-120.journal > -rw-r-----+ 1 root systemd-journal 4,0M Mai 26 13:37 > user-2012@0004fa4c02142cad-f97563ed0105bfb3.journal~ > -rw-r-----+ 1 root systemd-journal 3,6M Mai 26 15:25 > user-2012@0004fa4d8255b2df-43248028d422ca78.journal~ > -rw-r-----+ 1 root systemd-journal 3,7M Mai 27 10:57 > user-2012@0004fa5de40372db-d1f3c6428ddeec22.journal~ > -rw-r-----+ 1 root systemd-journal 4,3M Jun 2 12:46 > user-2012@0004fad81b8cd9d8-ed2861a9fa1b163c.journal~ > -rw-r-----+ 1 root systemd-journal 3,6M Jun 2 14:26 > user-2012@0004fad980139d4e-94ad07f4a8fae3cc.journal~ > -rw-r-----+ 1 root systemd-journal 3,8M Jun 5 14:41 > user-2012@0004fb160f2d5334-99462eb429f4cb7b.journal~ > -rw-r-----+ 1 root adm 200K Mai 11 10:21 > user-2012@54803afb1b1d42b387822c56e61bc168-0000000000011c75-0004ddb2be06d876.journal > -rw-r-----+ 1 root systemd-journal 3,8M Jun 11 21:14 user-2012.journal > -rw-r-----+ 1 root systemd-journal 3,6M Mai 26 14:04 > user-65534@0004fa4c62bf4a71-6b4c53dfc06dd588.journal~ > -rw-r-----+ 1 root systemd-journal 3,7M Jun 9 23:26 user-65534.journal > > > > > > > merkaba:/var/log> filefrag syslog* > syslog: 361 extents found > syslog.1: 202 extents found > syslog.2.gz: 1 extent found > [well sure, cause repacked] > syslog.3.gz: 1 extent found > syslog.4.gz: 1 extent found > syslog.5.gz: 1 extent found > syslog.6.gz: 1 extent found > > merkaba:/var/log> ls -lh syslog* > -rw-r----- 1 root adm 4,2M Jun 15 23:39 syslog > -rw-r----- 1 root adm 2,1M Jun 11 16:07 syslog.1 > > > > So we have ten times the extents on some systemd journal files than on > rsyslog. > > > With BTRFS RAID 1 on SSD with compress=lzo, so the 361 extents of syslog > may be due to the size limit of extents on compressed BTRFS filesystems. > > Anyway, since it is flash, I never bothered about the fragmentation. > > Ciao, > -- > Martin 'Helios' Steigerwald - http://www.Lichtvoll.de > GPG: 03B0 0D6C 0040 0710 4AFA B82F 991B EAAC A599 84C7 > -- > 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 -- === Hugo Mills: hugo@... carfax.org.uk | darksatanic.net | lug.org.uk === PGP key: 65E74AC0 from wwwkeys.eu.pgp.net or http://www.carfax.org.uk --- If the first-ever performance is the première, is the --- last-ever performance the derrière?
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