Linux学习之文件系统zfs性能优化
How to Improve ZFS performance
https://icesquare.com/wordpress/how-to-improve-zfs-performance/
In this tutorial, I will show you how to improve the performance of your ZFS using the affordable consumer-grade hardware (e.g., Gigabit network card, standard SATA non-SSD hard drives, consumer-grade motherboard etc.).
Many people found a problem on their ZFS system. The speed is slow! It is slow to read or write files to the system. In this article, I am going to show you some tips on improving the speed of your ZFS file system.
Notice that this article was originally based on ZFS on FreeBSD. Although most concepts can be applied to Linux, you may want to check out these two articles: ZFS: Linux VS FreeBSD and ZFS On Linux Emergency Recovery Guide. I always go back to the second article to rescure my ZFS data after rebooting my Linux server to a newer kernel.
This article is about how to build a single node ZFS server. If you are interested in implementing multiple-nodes ZFS system / ZFS clusters, please check here for details.
https://icesquare.com/wordpress/zfs-linux-vs-freebsd/
https://icesquare.com/wordpress/how-to-fix-the-mess-created-by-zfs-on-linux-after-update/
Table of Content
A Good 64-bit CPU + Lots of Memory
Tweaking the Boot Loader
Use Disks with the Same Specifications
Use a Powerful Power Supply
Enable Compression
Identify the Bottleneck
Keep Your ZFS up to Date
Understand How the ZFS Caching Works
More Disk = Faster
Use a Combination of Strip and RAIDZ If Speed Is Your First Concern.
Distribute Your Free Space Evenly (How to Rebalance ZFS)
Make Your Zpool Expandable
Backup the Data on a Different Machine, Not on the Same Zpool
Rsync or ZFS Send?
Did You Enable Dedup? Disable It!
Reinstall Your Old System
Connect Your Disks via High Speed Interface
Do Not Use up All Spaces
Use AHCI, Not IDE
Refresh Your Zpool
Great Performance Settings
My Settings
Improve ZFS Performance: Step 1 A Good 64-bit CPU + Lots of Memory
Traditionally, we are told to use a less powerful computer for a file/data server. That’s not true for ZFS. ZFS is more than a file system. It uses a lot of resources to improve the performance of the input/output, such as compressing data on the fly. For example, suppose you need to write a 1GB file. Without enabling the compression, the system will write the entire 1GB file on the disk. With the compression being enabled, the CPU will compress the data first, and write the data on the disk after that. Since the compressed data is smaller, it takes shorter time to write to the disk, which results a higher writing speed. The same thing can be applied for reading. ZFS can cache the file for you in the memory, it will result a higher reading speed.
That’s why a 64-bit CPU and higher amount of memory is recommended. I recommended at least a Quad Core CPU with 4GB of memory (Personally I use Xeon and i7, with at least 20GB of memory).
Please make sure that the memory modules should have the same frequencies/speed. If you mix them with different speed, try to group the memories with same speed together., e.g., Channel 1 and Channel 2: 1333 MHz, Channel 3 and Channel 4: 1600 MHz.
Let’s do a test. Suppose I am going to create a 10GB file with all zero. Let’s see how long does it take to write on the disk:
1 | #CPU: i7 920 (A 4 cores/8 threads CPU from 2009) + 24GB Memory + FreeBSD 9.3 64-bit |
That’s 1.6GB/s! Why is it so fast? That’s because it is a zero based file. After the compression, a compressed 10GB file may result in few bytes only. Since the performance of the compression is highly depended on the CPU, that’s why a fast CPU matters.
Now, let’s do the same thing on a not-so-fast CPU:
1 | #CPU: AMD 4600 (2 cores) + 5GB Memory + FreeBSD 9.3 64-bit |
That’s 434MB/s only. See the difference?
Improve ZFS Performance: Step 2 Tweaking the Boot Loader Parameters
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