Btrfsの構造

Transcript

1. Btrfs ͷػೳɾಛ௃
   BtrfsͬͯͲΜͳϑΝΠϧγεςϜ?
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2. Btrfs ͷػೳɾಛ௃
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3. Btrfs ͷػೳɾಛ௃
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   . Copy On Write
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4. Btrfs ͷػೳɾಛ௃
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   . Journal
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5. Btrfs ͷػೳɾಛ௃
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6. Btrfs ͷػೳɾಛ௃
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7. Btrfs ͷػೳɾಛ௃
   .
   . Journal ͷऑ఺
   ʮδϟʔφϧʯͱʮຊମʯͱೋճॻ͔ͳ͚Ε͹͍͚ͳ͍
   σʔλ΋δϟʔφϧԽ͢Δͷ͸ޮ཰͕ѱ͍
   ϝλσʔλͳΒ͍͚Δ
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8. Btrfs ͷػೳɾಛ௃
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9. Btrfs ͷػೳɾಛ௃
   .
   . Copy On Write
   Ұճ͔͠ॻ͔ͳ͍͍ͯ͘
   σʔλɾϝλσʔλ྆ํͷ੔߹ੑΛอͭͷʹ࢖͑Δ
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10. Btrfs ͷػೳɾಛ௃
    .
    .
    εφοϓγϣ
    οτ
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11. Btrfs ͷػೳɾಛ௃
    .
    .
    σϑϥά
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12. Btrfs ͷػೳɾಛ௃
    .
    . Quota
    QGroup ͱݺ͹ΕΔಛघͳ quota
    εφοϓγϣ
    οτ͕͋ΔͷͰʮڞ༗σʔλʯ͕ଘࡏ͢Δ
    ʮશମͷαΠζʯͱʮڞ༗͞Ε͍ͯͳ͍αΠζʯʹΑΔ੍ݶ͕Ͱ͖Δ
    ڈ೥ͷ Software Design10 ݄߸ʹࡌͬͯ·͢
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13. Btrfs ͷػೳɾಛ௃
    .
    . Ext2/3 ͔Βͷ convert
    ext2/3 ͷσʔλ͕ͦͷ··ม׵Ͱ͖·͢
    ؾʹ͍Βͳ͚Ε͹ݩʹ໭ͤ·͢
    2013-06-14 13 / 51
    

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14. Btrfs ͷػೳɾಛ௃
    .
    .
    ͦͷଞ
    16EiB ·Ͱ࢖͑Δ (XFS ͷ 2 ഒ!)
    checksum ͕͋Δ͔ΒϒϩοΫͷ੔߹ੑνΣ
    οΫ OK!
    ಁաతѹॖͰ༰ྔઅ໿!
    RAID Ͱ৴པੑ޲্!
    send/receive Ͱޮ཰తͳόοΫΞοϓ!
    Hot add/remove ͰΒ͘Β͘σΟεΫަ׵!
    dedup Ͱॏෳഉআ!
    SSD ༻࠷దԽ΋͋ΔΑ!
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15. Btrfs ͷػೳɾಛ௃
    .
    .
    কདྷతʹ
    ॻ͖͜Έͱಉ࣌ʹࣗಈ dedup
    hot data tracking ͰΑ͘ΞΫηε͢ΔϑΝΠϧΛ SSD ʹΩϟ
    ογϡ!
    fsck?
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16. Btrfs ͷػೳɾಛ௃
    .
    .
    ࢖͍ͨ͘ͳ͖ͬͯͨͰ͠ΐ?
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17. B ໦
    .
    . B ໦
    Btrfs ͷ΄ͱΜͲ͍ͨΔͱ͜ΖͰ࢖ΘΕΔσʔλߏ଄
    ͜Ε͕Θ͔Βͳ͍ͱ Btrfs ͕Θ͔Βͳ͍
    ͳΜͱ͍ͬͯ΋ “BtrFS” = “B-Tree File System” Ͱ͔͢Βͳ!
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18. B ໦
    .
    .
    ೋ෼୳ࡧ໦
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19. B ໦
    .
    . B ໦
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20. B ໦
    .
    . B ໦΁ͷૠೖ
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21. B ໦
    .
    .
    ෼ׂ
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22. B ໦
    .
    . CoW ૠೖ
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23. B ໦
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24. B ໦
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25. B ໦
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26. B ໦
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27. B ໦
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28. B ໦
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29. Btrfs ͷ໦
    .
    . Btrfs ͷ B ໦
    Key
    ΦϒδΣΫτ ID
    λΠϓ
    Φϑηοτ
    ϊʔυͱϦʔϑ
    Ұ൪Լ͕Ϧʔϑɺ࢒Γ͕Λϊʔυ
    ϦʔϑʹΩʔʹରԠ͢Δσʔλ͕อ؅͞ΕΔ
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30. Btrfs ͷ໦
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31. Btrfs ͷ໦
    .
    .
    ༷ʑͳ໦
    Root tree
    FS tree
    extent tree
    chunk tree
    device tree
    CSum tree
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32. Btrfs ͷ໦
    .
    . Root Tree
    جຊͷ໦!
    ଞͷ໦ͷ root Λอ࣋
    αϒϘϦϡʔϜߏ଄ͷऔಘ
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33. Btrfs ͷ໦
    .
    . FS Tree
    αϒϘϦϡʔϜɾεφοϓγϣ
    οτ͝ͱʹ FS tree ͷ root ͕͋Δ
    σΟϨΫτϦߏ଄
    i-node ৘ใ
    ϑΝΠϧσʔλҐஔ (extent address)
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34. Btrfs ͷ໦
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    . chunk ͱ extent
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35. Btrfs ͷ໦
    .
    . device treeɾCSum tree
    device tree
    Btrfs ʹొ࿥͞Ε͍ͯΔσόΠεͷ؅ཧ
    CSum tree
    4KB ͝ͱͷ checksum
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36. Btrfs ͷ໦
    .
    .
    ୳ͯ͠ΈΑ͏
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37. bootstrap
    Btrfs ͷ tree ΋ϑΝΠϧ΋શͯ extent address(࿦ཧΞυϨε) ͰΞΫ
    ηε
    Root tree ΋ extent address ͰΞΫηε͞ΕΔ
    chunk tree ࣗ਎΋
    Ͳ͏΍ͬͯ࠷ॳͷ extent address Λ෺ཧΞυϨεʹϚοϐϯά͢
    Δͷ?
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38. bootstrap
    .
    . superblock
    btrfs Ͱ།Ұ෺ཧతʹΞυϨε͕ܾ·͍ͬͯ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 ͔ΒׂΓ౰ͯΒΕΔ
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39. bootstrap
    .
    . system chunk
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40. bootstrap
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41. ࠷ۙͷ͜ͱ
    ࠷ޙʹ͜ͷ 1 ݄͙Β͍;Έ·ͬͯ͘Δ assert ʹ͍ͭͯ࿩͠·͢
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42. ࠷ۙ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
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43. ࠷ۙͷ͜ͱ
    .
    .
    Ωʔ୳ࡧͷ࠷దԽ
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44. ࠷ۙͷ͜ͱ
    .
    . snapshot aware defrag
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45. ࠷ۙͷ͜ͱ
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46. ࠷ۙͷ͜ͱ
    .
    . tree mod log
    B-tree ͷมߋ࣌ʹมߋલʹͲ͏͍͏஋͕ೖ͍͔ͬͯͨΛه࿥
    transaction ͝ͱʹϦηοτ͞ΕΔ
    ϝϞϦ্͚ͩͰσΟεΫʹ͸ॻ͔Εͳ͍
    ͜ΕͰʮੲͷ B-treeʯΛͱΓ͕ͩͦ͢Ε͕όάͬͯΔ?
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47. ࠷ۙͷ͜ͱ
    .
    .
    ݪҼ͸ʜͳΜͰͩΖ͏?
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48. ࠷ۙͷ͜ͱ
    ·͋ͱΓ͋͑ͣʮࣗಈσϑϥάʯ੾͓͚ͬͯ͹ (σϑΥϧτ:Φϑ) ͍͍ͱ
    ࢥ͏Α?
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49. ࠷ۙͷ͜ͱ
    .
    .
    ͓͠·͍
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50. 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
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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
    

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