What is a ZFS file system

today , Let's see ZFS, An advanced file system . We'll talk about where it comes from , What is it , And why it is so popular among technicians and enterprises . Although I come from America , But I prefer to use ZedFS instead of ZeeFS pronunciation , Because it sounds cooler . You can pronounce as you like .

ZFS The history of

Z file system （ZFS） from Matthew Ahrens and Jeff Bonwick On 2001 Created in .ZFS Aims to become Sun Microsystems Of OpenSolaris Next generation file system . 2008 year ,ZFS Be transplanted to FreeBSD. Same year , The beginning of a project will ZFS Migration to ​ ​Linux​​. however , because ZFS According to GNU The general public license is not compatible with the general development and distribution license , Therefore, it cannot be included in Linux The kernel . To solve this problem , majority Linux The distribution provides installation ZFS Methods .

Oracle acquisition Sun Microsystems Not long after ,OpenSolaris Become a close source . ZFS All further development of has also become a closed source . ZFS Many developers of are dissatisfied with this transformation event . Because of this decision , Two thirds of the core ZFS developer , Include Ahrens and Bonwick, I am leaving Oracle. They are with other companies 2013 year 9 Month created OpenZFS project . The project took the lead in ZFS Open source development .

Let's go back to the license issue mentioned above . because OpenZFS Project and Oracle It's separate. , So some people may wonder why they won't change the license to be the same as GPL Compatible things , So it can be included in Linux The kernel . according to OpenZFS What the website says , Changing the license will involve connecting anyone who contributes code to the current OpenZFS The implementation of （ Including the initial , common ZFS Code , until OpenSolaris） And get their permission to change the license . Since this work is almost impossible （ Because some contributors may be dead or hard to find ）, They decided to keep their licenses .

What is? ZFS？ What are its characteristics ？

As I said before ,ZFS Is an advanced file system . therefore , It has some interesting features . Such as ：

• Storage pool
• Copy on write
• snapshot
• Data integrity verification and automatic repair
• RAID-Z
• The maximum single file size is 16 EB（1 EB = 1024 PB）
• Maximum 256 One quadrillion （256*1015 ） Of ZB（1 ZB = 1024 EB） The storage

Let's break down these functions .

Storage pool

Unlike most file systems ,ZFS A combination of file system and volume manager functions . This means different from other file systems ,ZFS You can create file systems that span a series of drives or pools . More Than This , You can also add storage to the pool by adding additional drives . ZFS Will handle partitioning and formatting .

Copy on write

Copy-on-write Is another interesting （ And it's cool ） The function of . On most file systems , When data is overwritten , It will be lost forever . stay ZFS On , New information is written to different blocks . After writing , File system metadata will be updated to point to new information . This ensures that if the system crashes during writing （ Or something else happens ）, Old data will be retained . This also means that the system does not need to run after a system crash fsck.

snapshot

Copy-on-write Introduce another ZFS function ： snapshot . ZFS Use snapshots to track changes in the file system . “ The snapshot contains the original version of the file system , The real-time file system contains any changes made since the snapshot was taken . No use of extra space . When new data is written to the real-time file system , A new block will be allocated to store this data .“ After deleting the file , The snapshot reference will also be deleted . therefore , Snapshots are mainly used to track changes to files , But it does not include the addition and creation of files .

Snapshots can be mounted read-only , To restore the previous version of the file . The real-time system can also be rolled back to the previous snapshot . All changes made since the snapshot will be lost .

Data integrity verification and automatic repair

Whenever new data is written to ZFS when , It will create a checksum for the data . When reading this data , The checksum... Will be verified . If the checksum does not match , be ZFS Know that an error has been detected . then ,ZFS Will automatically attempt to correct the error .

RAID-Z

ZFS Can handle RAID Without any additional software or hardware . It is as expected ,ZFS Have their own RAID Realization ：RAID-Z. RAID-Z It's actually RAID-5 A variant of . however , It aims to overcome RAID-5 Error writing hole ,“ The data and parity information become inconsistent after accidental restart ”. To use the basic level RAID-Z（RAID-Z1）, You need at least two disks for storage , One for parity . RAID-Z2 At least two storage drives and two drives for parity are required . RAID-Z3 At least two storage drives and three drives for parity are required . When a drive is added to RAID-Z Pool time , They must be in 2 Add multiple of .

Huge storage potential

establish ZFS when , It is designed as the last word in the file system . In most 64 Bit file system ,ZFS The creator decided to jump directly to 128 Bits in order to prove it in the future . It means ZFS“ The capacity provided is 32 or 64 Bit system 16 Billion times ”. in fact ,Jeff Bonwick（ One of the founders ） Express , For one “ Completely fill 128 Bit storage pool provides power , It actually requires more energy than a boiling ocean .”

How to install ZFS？

If you want to use it out of the box ZFS, You need to install FreeBSD Or use illumos The kernel's operating system . illumos yes OpenSolaris A branch of the kernel .

in fact , Yes ZFS Your support is some experienced Linux User choice BSD One of the main reasons .

If you want to in Linux Try ZFS, It can only be used as a storage file system . as far as I am concerned , No, Linux The distribution gives you the ability to install... Out of the box ZFS The option to . If you are interested in Linux Try ZFS, that Linux Upper ZFS The project has many tutorials on how to do this .

Warning

This paper introduces ZFS The advantages of . Now let me tell you one ZFS Quick questions for . Use RAID-Z It can be expensive , Because how many drives do you need to buy to add storage space .

Have you ever used ZFS Do you ？ What was your experience ？ Please let us know in the comments below .

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This paper addresses ：​ ​https://www.linuxprobe.com/what-is-zfs.html​​