RAID setup. This HOWTO is deprecated the Linux RAID HOWTO is maintained as a wiki by the linuxraid community at httpraid. This tutorial will guide you on how to install and configure a complete mail server with Postfix and rainloop webmail client in Debian 9 release. The Software RAID HOWTO RAID setup. Next. Previous. Contents. This HOWTO is deprecated the Linux RAID HOWTO is maintained as a wiki by the. If your product is not listed above, please visit the product page. You want to install Ubuntu on your Windows computer, dont you The thing is, youre not 100 certain, yet. Fortunately, there are many ways in which you can try. In this article, we will explain how to install and configure the latest official version of Nagios Core and Nagios Plugins from sources in Debian and Ubuntu. A costeffective solution where hardware RAID data protection and performance is a requirement. The MegaRAID SAS 92714i SATA and SAS RAID controllers dualcore RAID. How To Install Debian On Software Raid' title='How To Install Debian On Software Raid' />This is what you need for any of the RAID levels. A kernel. Preferably a kernel from the 2. Alternatively. a 2. How To Install Debian On Software Raid' title='How To Install Debian On Software Raid' />RAID patches applied. The RAID tools. Patience, Pizza, and your favorite caffeinated beverage. All of this is included as standard in most GNULinux distributions. If your system has RAID support, you should have a file called. Remember it, that file is your friend. If you do not have. RAID support. See what the. It should tell you that. RAID personality eg. RAID mode registered, and. RAID devices are currently active. Create the partitions you want to include in your RAID set. The RAID tools are included in almost every major Linux distribution. IMPORTANT. If using Debian Woody 3. This raidtools. 2 is a modern version of the old raidtools. You can download the most recent mdadm tarball at. Issue a nice make install to compile and then. If using an RPM based distribution, you can download and install. RPM. rpm ihv mdadm 1. If using Debian Woody 3. Gentoo has this package available in the portage tree. There you can. Other distributions may also have this package available. Now, lets. go mode specific. Ok, so you have two or more partitions which are not necessarily the. Set up the etcraidtab file to describe your. I set up a raidtab for two disks in linear mode, and the file. Spare disks are not supported here. If a disk dies, the array dies. Theres no information to put on a spare disk. Youre probably wondering why we specify a chunk size here. Well, youre completely right, its odd. Just put in some. Ok, lets create the array. Run the command. mkraid devmd. This will initialize your array, write the persistent superblocks, and. If you are using mdadm, a single command like. The parameters talk for themselves. The output might look like this. K. mdadm array devmd. Have a look in procmdstat. You should see that the array is running. Now, you can create a filesystem, just like you would on any other. You have two or more devices, of approximately the same size, and you. Set up the etcraidtab file to describe your configuration. An. example raidtab looks like. Like in Linear mode, spare disks are not supported here either. RAID 0. has no redundancy, so when a disk dies, the array goes with it. Again, you just run. This should initialize the superblocks and. Have a look in procmdstat to see whats. You should see that your device is now running. You have two devices of approximately same size, and you want the two. Eventually you have more devices, which. Set up the etcraidtab file like this. If you have spare disks, you can add them to the end of the device. Remember to set the nr spare disks entry correspondingly. Ok, now were all set to start initializing the RAID. The mirror must. be constructed, eg. Issue the. mkraid devmd. Check out the procmdstat file. It should tell you that the devmd. ETA of the completion of the reconstruction. Reconstruction is done using idle IO bandwidth. So, your system. should still be fairly responsive, although your disk LEDs should be. The reconstruction process is transparent, so you can actually use the. Try formatting the device, while the reconstruction is running. It. will work. Also you can mount it and use it while reconstruction is. Of Course, if the wrong disk breaks while the reconstruction. Note I havent tested this setup myself. The setup below is. I have actually had up running. If you. use RAID 4, please write to the. You have three or more devices of roughly the same size, one device is. Eventually you have a number of devices you wish to use as. Set up the etcraidtab file like this. If we had any spare disks, they would be inserted in a similar way. Your array can be initialized with the. You should see the section on special options for mke. You have three or more devices of roughly the same size, you want to. Eventually you have a number of devices to. If you use N devices where the smallest has size S, the size of the. N 1. This missing space is used for. Thus, if any disk fails, all data. But if two disks fail, all data is lost. Set up the etcraidtab file like this. If we had any spare disks, they would be inserted in a similar way. And so on. A chunk size of 3. B is a good default for many general purpose. The array on which the above raidtab is. GB 3. 6 GB remember the n 1 7 1 3. It holds an ext. 2 filesystem with a 4 k. B block size. You could. Ok, enough talking. You set up the etcraidtab, so lets see if it. Run the. mkraid devmd. Hopefully your disks start working. Have a look. in procmdstat to see whats going on. If the device was successfully created, the reconstruction process has. Your array is not consistent until this reconstruction. However, the array is fully functional except. See the section on special options for mke. Ok, now when you have your RAID device running, you can always stop it. With mdadm you can stop the device using. S devmd. 0. and re start it with. R devmd. 0. Instead of putting these into init files and rebooting a zillion times. Back in The Good Old Days TM, the raidtools would read your. However, this would. This is unfortunate if you want to boot on a RAID. Also, the old approach led to complications when mounting filesystems. RAID devices. They could not be put in the etcfstab file as usual. The persistent superblocks solve these problems. When an array is. This allows the kernel to read. RAID devices directly from the disks involved. You should however still maintain a consistent etcraidtab file, since. The persistent superblock is mandatory if you want auto detection of. RAID devices upon system boot. This is described in the. Autodetection section. The chunk size deserves an explanation. You can never write. If you had two disks and wanted. Hardware just doesnt support that. Instead, we choose some. A write of 1. 6 k. B with a chunk. size of 4 k. B, will cause the first and the third 4 k. B chunks to be. written to the first disk, and the second and fourth chunks to be. RAID 0 case with two disks. Thus. for large writes, you may see lower overhead by having fairly large. Chunk sizes must be specified for all RAID levels, including linear. However, the chunk size does not make any difference for linear. For optimal performance, you should experiment with the value, as well. The argument to the chunk size option in etcraidtab specifies the. So 4 means 4 k. B. RAID 0. Data is written almost in parallel to the disks in the. Actually, chunk size bytes are written to each disk. If you specify a 4 k. B chunk size, and write 1. B to an array of three. RAID system will write 4 k. B to disks 0, 1 and 2, in. B to disk 0. A 3. B chunk size is a reasonable starting point for most arrays. Moscow The Power Of Submission Download Adobe on this page. But. the optimal value depends very much on the number of drives involved. Experiment with it, to get the best performance. RAID 0 with ext. The following tip was contributed by. There is more disk activity at the beginning of ext. On a single disk, that does not matter, but it can hurt RAID0, if all. Example With 4k stripe size and 4k block size, each block occupies one stripe. With two disks, the stripe disk product is 2k8k. The default. block group size is 3. Unfortunately, the block group size can only be set in steps of 8 blocks. If you add a disk, the stripe disk product is 1. The load caused by disk activity at the block group.