A few months ago i posted an article explaining how redundant arrays of inexpensive disks raid can provide a means for making your disk accesses faster and more reliable in this post i report on numbers from one of our servers running ubuntu linux. High performance scst iscsi target on linux software raid. Linux sofrware array performance tuning im not a big fan of linux software array, mostly just use it for local disks, not for disks using for cluster file systems. For any organization trying to achieve optimum performance, the underlying hardware configuration is extremely critical. This howto does not treat any aspects of hardware raid. For pure performance the best choice probably is linux md raid, but. There are countless open source software support under this platform. These numbers are consistent with what i get using a 6disk linux raid 10. Because the linux operating system is not a websphere application server product, be aware that it can change and results can vary. Fourth reason is the inefficient locking decisions. Speaking of raid levels, raid 45 will never give you good performance, that is comparing to raid0 or raid10. Running simple commands like ls takes several seconds to complete. The hw raid was a quite expensive usd 800 adaptec sas31205 pci express 12sataport pcie x8 hardware raid card.
Also, just did some testing on the latest mlc fusionio cards and we used 1, 2 and 3 in various combinations on the same machine. If your workloads require more iops than a single disk can provide, you need to use a software raid configuration of multiple disks. When you look into the code, you see the md driver is not fully optimized. Raid0 with 2 drives came in second and raid0 with 3 drives was the fastest by quite a margin 30 to 40% faster at most db ops than any nonraid0 config. I get 121mbs read and 162mbs write with ext4, or 120176 using an external journal device.
Disks are block devices and we can access related kernel data structures through sysfs. In testing both software and hardware raid performance i employed six 750gb samsung sata drives in three raid configurations 5, 6, and 10. A lot of software raids performance depends on the. How to create a software raid 5 in linux mint ubuntu. It is tough to beat software raid performace on a modern cpu with a fast disk controller. The performance tuning guide describes how to optimize the performance of a system running red hat enterprise linux 6. When i do dd write and read testing using 4k, 8k, 16k bytesizes, im only getting a write speed of 2225 mbsec. Why is it that software raid on current systems still gets less performance than hardware counterparts. Performance tuning for software raid6 driver in linux calsoft inc. Linux software raid has native raid10 capability, and it exposes three possible layout for raid10style array. Speeding up a filesystems performance by setting it up on a tuned. Performance optimization for linux raid6 for devmd2.
Software vs hardware raid performance and cache usage server. Linux software raid can work on most block devices such as sata, usb, ide or scsi devices, or a combination of these. This course will teach you the appropriate tools, subsystems, and techniques you need to get the best possible performance out of linux. Software raid 5 write performance i have a media server i set up running ubuntu 10. Using mdadm linux soft raid were ext4, f2fs, and xfs while btrfs raid0raid1 was also tested using that filesystems integratednative raid capabilities. We can use the kernel data structures under sys to select and tune io queuing algorithms for the block devices. Centos, xeon 1230, 16 gb ram, 2x1tb ssd in raid1 mdadm. Benchmark performance is often heavily based on disk io performace.
Raid 0 with 2 drives came in second and raid 0 with 3 drives was the fastest by quite a margin 30 to 40% faster at most db ops than any non raid 0 config. We can use full disks, or we can use same sized partitions on different sized drives. International technical support organization linux performance and tuning guidelines july 2007 redp428500. Performance tuning with chunk size and stride values. Tips and recommendations for storage server tuning beegfs. The important distinction is that unbuffered character devices provide direct access to the device, while. Individually they benchmark using the ubuntus mdadm gui. Speed up linux software raid various command line tips to increase the. Block and character are misleading names for device types. Written for system administrators, power users, tech managers, and anyone who wants to learn about raid technology, managing raid on linux sidesteps the often. I have a dell poweredge t105 at home and i am purchasing the following. Fink 2001, paperback at the best online prices at ebay. How to improve server performance by io tuning part 1. If properly configured, theyll be another 30% faster.
The only solution is to install operating system with raid0 applied logical volumes to safe your important files. I am the proud user of linux software raid on my home server, but for a proper enterprise system i would try to avoid it. Hard disks, linux, raid, server performance tuning. The difference is not big between the expensive hw raid controller and linux sw raid. To have a raid0 device running a full speed, you must have partitions from different disks. For raid5 linux was 30 % faster 440 mbs vs 340 mbs for reads. Linux performance tuning lfs426 keeping your linux systems running optimally is a missioncritical function for most linux it professionals.
Linux performance tuning idea to optimize linux system. Such raid features have persuaded organizations to use it on top of raw devices. Here are our latest linux raid benchmarks using the very new linux 4. These layouts have different performance characteristics, so it is important to choose the right layout for your workload. It also documents performancerelated upgrades in red hat enterprise linux 6. While this guide contains procedures that are fieldtested and proven, red hat recommends that you properly test all planned configurations in a testing environment before applying it to a production. Software raid how to optimize software raid on linux using. According to many mailing lists and the opinion of the linux raid author, raid10 with layout f2 far seems to preform best while still having redundancy. Most all any optimization and new features reconstruction, multithreaded tools, hotplug, etc. Ive noticed some performance issues with my 8drive software raid6 2tb, 7200rpm drives. This lead to massive overhead in some common situations. Depending on the array, and the disks used, and the controller, you may want to try software raid.
Linux software raid often called mdraid or mdraid makes the use of raid. Please remember with raid10 50% of your hard disk space will go to redundancy, but performance is almost the same as raid0 stripe. An introduction to raid and linux planning and architecture of your raid system building a software raid software raid tools and references building a hardware raid performance and tuning of your raid system raid has become the lowcost solution of choice to deal with the everincreasing demand for data storage space. Hey, i have worked with linux for some time, but have not gotten into the specifics of hard drive tuning or software raid. Optimize your linux vm on azure azure linux virtual. We just need to remember that the smallest of the hdds or partitions dictates the arrays capacity. A lot of software raids performance depends on the cpu. There is great software raid support in linux these days. Raid has become the lowcost solution of choice to deal with the everincreasing demand for data storage space. You should then ask yourself if the software raid found in linux is comprehensive enough for your system. Mdadm is linux based software that allows you to use the operating system to create and handle raid arrays with ssds or normal hdds. Raid is usually implemented either in hardware on intelligent disk storage that exports the raid volumes as luns, or in software by the operating system. The real performance numbers closely match the theoretical performance i described earlier.
Software raid how to optimize software raid on linux. The redundant array of independent disks raid feature allows you to spread data across the drives to increase capacity, implement data redundancy, and increase performance. I still prefer having raid done by some hw component that operates independently of the os. Playing back a 1080p video with plex over ethernet regularly freezes, requiring several seconds to rebuffer. Another level, linear has emerged, and especially raid level 0 is often combined with raid level 1. Yes, linux implementation of raid1 speeds up disk read operations by a factor of two as long as two separate disk read operations are performed at the same. The technote details how to convert a linux system with non raid devices to run with a software raid configuration.
Because azure already performs disk resiliency at the local fabric layer, you achieve the highest level of performance from a raid0 striping configuration. For better performance raid 0 will be used, but we cant get the data if one of the drive fails. Also, are there any knobspulleysledgers in the linux kernel so that i can maximize raid operation performance. Performance tuning for software raid6 driver in linux. Performance tuning guide red hat enterprise linux 6 red.
In general, software raid offers very good performance and is relatively easy to maintain. Compiler optimization may not have been done properly. The raid6 device is created from 10 disks out of which 8 were data disks and 2 were paritydisks. So getting as much disk io as possible is the real key. Linux sofrware array performance tuning fibrevillage. Ive personally seen a software raid 1 beat an lsi hardware raid 1 that was using the same drives. When you have a performance concern, check the operating system settings to determine if these settings are appropriate for your application. Linux performance tuning and capacity planning by matthew sherer and jason r. For what performance to expect, the linux raid wiki says about raid 5. Creating software raid0 stripe on two devices using. Test software used to measure data for this article. Plug them in and they behave like a big and fast disk. Why speed up linux software raid rebuilding and resyncing. Given that our current bottleneck is the disk io, it would take a sincere effort to saturate the cpu with raiddisk operations youd.
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