Zeta file system

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Zettabyte File System

Zettabyte File System
Robert Miłkowski System Group Manager Wirtualna Polska

Zettabyte File System

What is ZFS?
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Completely new 128-bit file system Integrated volume manager Best data integrity Simple management Great performance
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Zettabyte File System

Traditional file systems


No protection for silent datacorruption


Can't guarantee correct data



Hard to manage
Partitions, slices, labels ● Not flexible storage space management ● Lots of limits ● Platform dependent




Too much complexity with FS+VM
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Zettabyte File System

Wish list
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Make it SCALABLE Make it MANAGABLE Make it DYNAMIC Make it SAFE Make it EASIER
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Let's do it from the scratch


Pooled storage
No need for slices, partitions, volumes, etc. ● Make as many file systems as you want for free




End-to-end data integrity


Guarantee that application gets correct data Always consistent on disk – meta and user data
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Transactional


Zettabyte File System

TraditionalFS+VM
FS FS FS

Volume

Volume

Volume

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Zettabyte File System

ZFS pooled storage
ZFS ZFS ZFS

Storage Pool

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Zettabyte File System

ZFS pooled storage - example

# zpool create home c5t40d0 c5t40d1 c5t40d2 c5t40d3 # zfs create home/milek # zfs create home/www # zfs create home/milek/mail # zfs set compression=onhome/milek/mail # # zfs list NAME USED AVAIL REFER MOUNTPOINT home 72K 18.0T 10K /home home/milek 18.5K 18.0T 9.50K /home/milek home/milek/mail 9K 18.0T 9K /home/milek/mail home/www 9K 18.0T 9K /home/www #
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Zettabyte File System

ZFS Quoas & Reservations
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You can reserve space for a given fs You can set quota for a given fs quota/reservation forhierarchies No quotas for uid/gid

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Zettabyte File System

Data integrity


Both data and meta-data are checksumed


No silent data corruption



Everything is Copy-On-Write
Never overwrite live data ● Always consistent on disk ● No need for fsck-like utility


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Zettabyte File System

End-to-end data integrity
●Checksum checked after block is in memory
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Whole IO path is checked Corrects driver bugs, phantom writes, etc.



Checksum and data block stored separately
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Checksum is stored in parent block Entire pool is self-validating



Protects from accidental overwrites
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Zettabyte File System Zettabyte File System

ZFS Self Healing
ApplicationApplication Application

ZFS Mirror

ZFS Mirror

ZFS Mirror

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Zettabyte File System

Data integrity - example
# zpool create home mirror c5t40d0 c5t40d1 # cd /home/ ; ncftp sol-nv-b39-x86-dvd.iso # digest -a md5 sol-nv-b39-x86-dvd.iso a09a7af5ad25a980fa907b552a5bd523 # dd if=/dev/zero of=/dev/rdsk/c5t40d0s0 bs=1024k # digest -a md5 sol-nv-b39-x86-dvd.isoa09a7af5ad25a980fa907b552a5bd523

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Zettabyte File System

Ditto blocks
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Can't read data block – EIO Can't read meta-data block – part of fs is gone In most cases meta-data is less than 2% So replicate meta-data blocks


Additional to pool protection (mirror, raid-z)

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Zettabyte File System

Ditto blocks
3xmeta-data blocks with pool information ● 2x meta-data blocks with fs information ● 1x user data blocks



Planned are 2x and 3x user data ditto blocks per fs



Keep each copy on separate vdev ● Spread block with only one drive


With user ditto blocks you get mirroring on single disk
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Zettabyte File System

RAID-5


RAID-5 write hole – silent data...
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