In this post we will be going through the steps to configure software raid level 0 on linux. A combination of drives makes a group of disks to form a raid array or a set of raid which can be a minimum of 2 disks connected to a raid controller and making a logical volume or more, it can be a combination of more drives in a group. It addresses a specific version of the software raid layer, namely the 0. Difference between software raid and hardware raid. Since you mention server most likely there is hardware raid present. The md driver in the linux kernel is an example of a raid solution that is completely hardware independent.
My own tests of the two alternatives yielded some interesting results. Raid 5 vs raid 10 recommended raid for safety and performance. Raid contains a group or a set of arrays set of disks. On the software raid side, the ext3 configuration is the same as the ext3alignwb hardware configuration, the plain xfs option the same as hardxfsalign, and the xfslogalign the same as the xfsdlalign hardware configuration. A linux software raid tutorial oakton community college. This howto describes how to use software raid under linux. The raid support in consumer level intel chipsets is known as fake raid, because it is really software raid masquerading as hardware. You have to keep in mind that if hardware raid is broken, you need to rebuild the raid with the same hardware vendor. Software raid 6 vs hardware does anyone know the performance difference under linux with modern software and hardware. It does not work all that well, especially in linux. Raid can be implemented with either hardware raid controller or software. While a file server setup to use software raid would likely sport a quad core cpu with 8 or 16gb of ram, the relative differences in performance. Numerous operating systems support raid configuration, including those from apple, microsoft, various linux flavors as well as openbsd. The independent disks attach to the hardware interface.
Software raid implements the various raid levels in the kernel disk block device code. Raid article from the wikipedia, the free encyclopedia. What is the difference between hardware raid and software. How to set up a software raid on linux addictivetips. Hardware raid configuration is usually done via the system bios when the server boots up, and once configured, it is absolutely transparent to linux. Linux file systems are generally fragile enough without throwing software raid and questionable hardware into the mix. Mechanical drives hdds are typically used due to their large capacity over low prices.
Once the device is created, the configuration is normally stored in etcmdadmnf so the raid device will automatically reassembled on boot the commands roughly equivalent to the above plus mounting as raid are. The performance of a softwarebased array is dependent on the server cpu performance and load. All i can find is vague, conflicting comments with nothing to back them up. Software raid also works with cheaper ide disks as well as scsi disks. This became necessary since i am running linux and windows in parallel and now need the redundancy for both os im am going to. Software vs hardware raid nixcraft linux tips, hacks. It offers the cheapest possible solution, as expensive disk controller cards or hotswap chassis 1 are not required. This is the raid layer that is the standard in linux2. Hardware and software raid are two different worlds. Comparison of software raid on windows versus linux. Linux software raid provides redundancy across partitions and hard disks, but it tends to be slower and less reliable than raid provided by a hardwarebased raid disk controller. Its also much more capable and powerful in recovery situations than hardware raid. Avoid it if you dont have to dual boot with windows, which has terrible software raid support. Windows software raid vs hardware raid ars technica.
The only problem is so many people assume raid backups and do not pay attention to the system until they have lost too many drives. How to set up software raid 1 on an existing linux. Raid devices, as most devices, have an entry in dev usually of the form devmd999 e. Well supported hardware raid controller ask ubuntu. With todays faster cpus, software raid outperforms hardware raid. Not to mention the performance hit under heavy io not having a dedicated hardware controller handling all the striping and parity operations. Software raid is a type of raid implementation that utilizes operating systembased capabilities to construct and deliver raid services.
Comparison of software raid on windows versus linux by angsuman chakraborty, gaea news network sunday, february 18, 2007. With todays fast cpus, software raid performance can excel against hardware raid. This means that every raid z write is a fullstripe write. In a true hardware raid, the operating system simply writes data to the hardware raid controller which handles the multiplicitous. Software raid disks attached to servers can be turned into raid arrays using builtin features on a number of operating systems. It sounds like you configured the raid via the bios though so definitely use that. Configure raid on loop devices and lvm over top of raid. Software vs hardware raid performance and cache usage server. Take a look on this document, i think its what you need.
So, what are the pros and cons of software raid vs. Raid 0 was introduced by keeping only performance in mind. If you configured the raid via software raid mdadm the use that. This article introduces the setup of software based raid setup on linux. In a hardware raid setup, the drives connect to a raid controller card inserted in a fast pciexpress pcie slot in a motherboard. Linux software raid vs hardware raid cards titlelinux software raid vs hardware raid cards so, if you read our benchmarks comparing windows 7, vista and ubuntu and are looking to find out more on what separates windows 7 and linux on the features front. On the software side, todays software raid is superfast at least with linux and bsd, extremely flexible, and highly integrated into oss.
We will be publishing a series of posts on configuring different levels of raid with its software implementation in linux. My experience with hardware and fakehardware raid is that as long as you stay with the same vendor, the raid metadata will be recognized ive seen this when moving drives between various hp, areca and lsi hardware raid controllers, and with intel, amd and even via hostraid i was pretty surprised when i connected a 250gb hard drive from some old amd desktop box to a hp g1 microserver, and. It has 8 disks and i would like to configure raid1 on the disks. The basic idea of raid redundant arrays of inexpensive disks is to combine multiple small, independent disk drives into an array of disk drives which yields performance and recoverability exceeding that of a single large expensive drive sled. Unlike hardware raid, software raid uses the processing power of the operating system in which the raid disks are installed. Wayne is right, if youre using linux, kernels soft raid works like charm. Linux md raid is exceptionally fast and versatile, but linux io stack is composed of multiple independent pieces that you need to carefully. If you are working as a linux system administrator or linux system engineer or you are already a storage engineer or you are planning to start your career in field of linux or you are preparing for any linux certification exam like rhce or you are preparing for linux admin interview then the the understanding of concept of raid become so important for you along with its configuration.
No matter how good software or hardware raid is it doesnt protect against the user or admin not monitoring the system. The softwareraid howto linux documentation project. The linux kernel contains an md driver that allows the raid solution to be completely hardware independent. Theres nothing inherently wrong with cpuassisted aka software raid, but you should use the software raid that. And it still does not prevent the need for actual backups not stored on the same system as the important data.
How to create a software raid 5 in linux mint ubuntu. Hardware raid solutions exist that operate as dedicated devices, usually as pci expansion cards or directly on the motherboard. Motherboard raid, also known as fake raid, is almost always merely biosassisted software raid, implemented in firmware and is closedsource, proprietary, nonstandard, and often buggy, and almost always slower than the timetested and reliable software raid found in linux. I am currently planning to buy a hardwareraid controller.
This also applies to reading and writing procedures. You can benchmark the performance difference between running a raid using the linux kernel software raid and a hardware raid card. Im trying to understand which way is the best to control 3 case fans on fractal r4. It can either be performed in the host servers cpu software raid, or in an external cpu hardware raid. The sun documentation states that you can either use the openboot promp utility called fcode or you can use software via the solaris os. Lets start the hardware vs software raid battle with the hardware side.
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