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Btrfsの構造
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naota
October 19, 2013
Programming
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Btrfsの構造
naota
October 19, 2013
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Transcript
Btrfs ͷػೳɾಛ BtrfsͬͯͲΜͳϑΝΠϧγεςϜ? 2013-06-14 1 / 51
Btrfs ͷػೳɾಛ 2013-06-14 2 / 51
Btrfs ͷػೳɾಛ . . Copy On Write 2013-06-14 3 /
51
Btrfs ͷػೳɾಛ . . Journal 2013-06-14 4 / 51
Btrfs ͷػೳɾಛ 2013-06-14 5 / 51
Btrfs ͷػೳɾಛ 2013-06-14 6 / 51
Btrfs ͷػೳɾಛ . . Journal ͷऑ ʮδϟʔφϧʯͱʮຊମʯͱೋճॻ͔ͳ͚Ε͍͚ͳ͍ σʔλδϟʔφϧԽ͢Δͷޮ͕ѱ͍ ϝλσʔλͳΒ͍͚Δ 2013-06-14
7 / 51
Btrfs ͷػೳɾಛ 2013-06-14 8 / 51
Btrfs ͷػೳɾಛ . . Copy On Write Ұճ͔͠ॻ͔ͳ͍͍ͯ͘ σʔλɾϝλσʔλ྆ํͷ߹ੑΛอͭͷʹ͑Δ 2013-06-14
9 / 51
Btrfs ͷػೳɾಛ . . εφοϓγϣ οτ 2013-06-14 10 / 51
Btrfs ͷػೳɾಛ . . σϑϥά 2013-06-14 11 / 51
Btrfs ͷػೳɾಛ . . Quota QGroup ͱݺΕΔಛघͳ quota εφοϓγϣ οτ͕͋ΔͷͰʮڞ༗σʔλʯ͕ଘࡏ͢Δ
ʮશମͷαΠζʯͱʮڞ༗͞Ε͍ͯͳ͍αΠζʯʹΑΔ੍ݶ͕Ͱ͖Δ ڈͷ Software Design10 ݄߸ʹࡌͬͯ·͢ 2013-06-14 12 / 51
Btrfs ͷػೳɾಛ . . Ext2/3 ͔Βͷ convert ext2/3 ͷσʔλ͕ͦͷ··มͰ͖·͢ ؾʹ͍Βͳ͚Εݩʹͤ·͢
2013-06-14 13 / 51
Btrfs ͷػೳɾಛ . . ͦͷଞ 16EiB ·Ͱ͑Δ (XFS ͷ 2
ഒ!) checksum ͕͋Δ͔ΒϒϩοΫͷ߹ੑνΣ οΫ OK! ಁաతѹॖͰ༰ྔઅ! RAID Ͱ৴པੑ্! send/receive ͰޮతͳόοΫΞοϓ! Hot add/remove ͰΒ͘Β͘σΟεΫަ! dedup Ͱॏෳഉআ! SSD ༻࠷దԽ͋ΔΑ! 2013-06-14 14 / 51
Btrfs ͷػೳɾಛ . . কདྷతʹ ॻ͖͜Έͱಉ࣌ʹࣗಈ dedup hot data tracking
ͰΑ͘ΞΫηε͢ΔϑΝΠϧΛ SSD ʹΩϟ ογϡ! fsck? 2013-06-14 15 / 51
Btrfs ͷػೳɾಛ . . ͍ͨ͘ͳ͖ͬͯͨͰ͠ΐ? 2013-06-14 16 / 51
B . . B Btrfs ͷ΄ͱΜͲ͍ͨΔͱ͜ΖͰΘΕΔσʔλߏ ͜Ε͕Θ͔Βͳ͍ͱ Btrfs
͕Θ͔Βͳ͍ ͳΜͱ͍ͬͯ “BtrFS” = “B-Tree File System” Ͱ͔͢Βͳ! 2013-06-14 17 / 51
B . . ೋ୳ࡧ 2013-06-14 18 / 51
B . . B 2013-06-14 19 / 51
B . . B ͷૠೖ 2013-06-14 20 / 51
B . . ׂ 2013-06-14 21 / 51
B . . CoW ૠೖ 2013-06-14 22 / 51
B 2013-06-14 23 / 51
B 2013-06-14 24 / 51
B 2013-06-14 25 / 51
B 2013-06-14 26 / 51
B 2013-06-14 27 / 51
B 2013-06-14 28 / 51
Btrfs ͷ . . Btrfs ͷ B Key ΦϒδΣΫτ
ID λΠϓ Φϑηοτ ϊʔυͱϦʔϑ Ұ൪Լ͕ϦʔϑɺΓ͕Λϊʔυ ϦʔϑʹΩʔʹରԠ͢Δσʔλ͕อ͞ΕΔ 2013-06-14 29 / 51
Btrfs ͷ 2013-06-14 30 / 51
Btrfs ͷ . . ༷ʑͳ Root tree FS tree extent
tree chunk tree device tree CSum tree 2013-06-14 31 / 51
Btrfs ͷ . . Root Tree جຊͷ! ଞͷͷ root Λอ࣋
αϒϘϦϡʔϜߏͷऔಘ 2013-06-14 32 / 51
Btrfs ͷ . . FS Tree αϒϘϦϡʔϜɾεφοϓγϣ οτ͝ͱʹ FS tree
ͷ root ͕͋Δ σΟϨΫτϦߏ i-node ใ ϑΝΠϧσʔλҐஔ (extent address) 2013-06-14 33 / 51
Btrfs ͷ . . chunk ͱ extent 2013-06-14 34 /
51
Btrfs ͷ . . device treeɾCSum tree device tree Btrfs
ʹొ͞Ε͍ͯΔσόΠεͷཧ CSum tree 4KB ͝ͱͷ checksum 2013-06-14 35 / 51
Btrfs ͷ . . ୳ͯ͠ΈΑ͏ 2013-06-14 36 / 51
bootstrap Btrfs ͷ tree ϑΝΠϧશͯ extent address(ཧΞυϨε) ͰΞΫ ηε Root
tree extent address ͰΞΫηε͞ΕΔ chunk tree ࣗ Ͳ͏ͬͯ࠷ॳͷ extent address ΛཧΞυϨεʹϚοϐϯά͢ Δͷ? 2013-06-14 37 / 51
bootstrap . . superblock btrfs Ͱ།ҰཧతʹΞυϨε͕ܾ·͍ͬͯΔ ύʔςΟγϣϯ ઌ಄͔Β 6410KiB, 6410MiB,
25610GiB, 1PiB root ͷ extent address root tree chunk tree system chunk ͷ chunk ใ chunk tree ͷϊʔυ, Ϧʔϑ system chunk ͔ΒׂΓͯΒΕΔ 2013-06-14 38 / 51
bootstrap . . system chunk 2013-06-14 39 / 51
bootstrap 2013-06-14 40 / 51
࠷ۙͷ͜ͱ ࠷ޙʹ͜ͷ 1 ݄͙Β͍;Έ·ͬͯ͘Δ assert ʹ͍ͭͯ͠·͢ 2013-06-14 41 / 51
࠷ۙͷ͜ͱ . . dump [42604.796633] BTRFS assertion failed: !memcmp_extent_buffer( b,
&disk_key, offsetof(struct btrfs_leaf, items[0].key), sizeof(disk_key)), file: fs/btrfs/ctree.c, line: 2444 2013-06-14 42 / 51
࠷ۙͷ͜ͱ . . Ωʔ୳ࡧͷ࠷దԽ 2013-06-14 43 / 51
࠷ۙͷ͜ͱ . . snapshot aware defrag 2013-06-14 44 / 51
࠷ۙͷ͜ͱ 2013-06-14 45 / 51
࠷ۙͷ͜ͱ . . tree mod log B-tree ͷมߋ࣌ʹมߋલʹͲ͏͍͏͕ೖ͍͔ͬͯͨΛه transaction ͝ͱʹϦηοτ͞ΕΔ
ϝϞϦ্͚ͩͰσΟεΫʹॻ͔Εͳ͍ ͜ΕͰʮੲͷ B-treeʯΛͱΓ͕ͩͦ͢Ε͕όάͬͯΔ? 2013-06-14 46 / 51
࠷ۙͷ͜ͱ . . ݪҼʜͳΜͰͩΖ͏? 2013-06-14 47 / 51
࠷ۙͷ͜ͱ ·͋ͱΓ͋͑ͣʮࣗಈσϑϥάʯ͓͚ͬͯ (σϑΥϧτ:Φϑ) ͍͍ͱ ࢥ͏Α? 2013-06-14 48 / 51
࠷ۙͷ͜ͱ . . ͓͠·͍ 2013-06-14 49 / 51
ϦϯΫ . . ࢀߟจݙ https://btrfs.wiki.kernel.org/ https://events.linuxfoundation.org/sites/events/files/ slides/LinuxCon_2013_NA_Eckermann_Filesystems_btrfs.pdf http://people.redhat.com/lczerner/files/btrfs_lczerner.pdf https://www.usenix.org/legacy/event/lsf07/tech/rodeh.pdf 2013-06-14
50 / 51
ϦϯΫ . . ը૾ http://www.flickr.com/photos/artofphotography-ramsner/9592744354 http://www.flickr.com/photos/surferbill/2506950772/ http://www.flickr.com/photos/rore/1304728223/ http://ja.wikipedia.org/wiki/ %E3%83%95%E3%82%A1%E3%82%A4%E3%83%AB: Binary_search_tree.svg
http://www.flickr.com/photos/protohiro/85504626/ http://www.flickr.com/photos/rubyji/74176893/ http://www.flickr.com/photos/rore/1304728223/ http://www.flickr.com/photos/dolfiedream/5060030894/ 2013-06-14 51 / 51