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ATA-RAID (or IDE-Raid)-controllers are a cheap way to get RAID (a way to let multiple hard disks look like a single disk) on a PC. Note: the Linux kernel also has a software RAID feature, for free of course! Even Windows NT/2000/XP ships usually with the 'stripe set feature'. However Linux' and Windows' software RAID are not compatible with each other. Windows 9x/ME does not have native RAID support at all. If you have multiple operating systems on your machine an ATA-Raid-adapter may be a good choice. You should also be aware of the down-side of hardware raid; should your controller fail you may, depending on the type of RAID you use, have to obtain a compatible controller to read your disks.ATA-RAID controllers are normal IDE controllers, the RAID is done by special drivers. Thus they are a kind of software RAID, which works only with that specific hardware. ('software' means: the computers main processor has to do the work) . The difference between the ATA-RAID controllers and normal IDE-controllers is mainly (beside the some bios), that ATA-RAID controllers tell the system, they are SCSI controllers. This is done, because Windows easily accepts 3rd party drivers for SCSI adapters (even during the first stages of setup) but it usually assumes, that IDE disks can be accessed by native Windows drivers (which don't know RAID).
Often, the ATA-RAID controller is just the second IDE-controller installed on a system, since usually the motherboard chipset already contains an IDE-controller. In that case the four disks you can have connected to the first IDE-controller appear under the device names /dev/hda ... /dev/hdd, but disks on the IDE-RAID Controller appear instead as /dev/hde ... /dev/hdh. However, these device names mean physical disks. The goal of a RAID-Controller is to let multiple physical disks appear to be a single disk. Thus, once you have configured a raid array, you should never again access the disks at hde...hdh. The information read from these devices will not be meaningful, and any attempt to write to them will likely destroy the whole array!If the Linux kernel recognizes an ATA-RAID array it will provide access to the first 'virtual' disk at /dev/ataraid/d0 . The second disk is /dev/ataraid/d1 (goes up to 15). The first partition on the first disk is: /dev/ataraid/d0p1 . That's it: access to the virtual raid devices is otherwise exactly the same as with ordinary hard disks.
Today, the only problem with these controllers is that some of the partitioning tools and most of the KNOPPIX-scripts related to disk partitions don't expect hard disks with the device names of ataraid disks.This document shows how to correct this in the most important scripts.
If you are successful in using ATARAID as described here you may wish to let these authors know that it works.If you experience any problems, especially data loss, please let me know and I will update this documentation.
If you have your hard disk connected to an ataraid adapter and you see disks and partitions of the type '/dev/hde' ... never touch them, if you value your data.
Unpack the files to a floppy. (Using a floppy is recommended until you are sure that everything works.) There are multiple ways to do this. Note: on some Linux systems you have to mount the floppy first, before you can access it, either by clicking on the 'floppy' icon or by typing
(KNOPPIX automatically mounts floppies.)
Now decompress and unpack the archive, using one of these three methods:
plugconffolder, then into
liband get the file
knoppix.sh. Copy this to the root of the floppy. It is recommended, not to remove the
knoppix.sh-file from its original position (it should appear twice on the floppy. ).
(or whatever the archive is called). To get
(Don't omit the trailing '.'.)
If you already have extracted the archive to
any other place on your machine run the
makefloppy.sh, found in the
plugconf/tools folder, and follow its
The floppy should now contain a folder
plugconf and a
knoppix floppyconfig and press the ENTER key. (At
this stage you may also press F2 to see a list of other valid
cheatcodes.) Now your partitions should be accessible via icons on the
cd /mnt/floppy. This will keep the floppy mounted until that window is closed! But you must close this window, as well as all programs accessing files or directories of the floppy, before you remove the floppy! (Find such programs with:
sudo lsof -D /mnt/floppyand
ps ax --forest.) Otherwise you risk data loss, and the floppy drive may be inaccessible until reboot.
knoppix home=...which was introduced in KNOPPIX 3.2 . The original persistent_home and a description you will find in the archive
knx_persistent_home_XXX.zipin the 3rd_party folder of the plugscript home page .
Note, that any method to make the home directory persistent requires at least one Linux writable disk partition on the ataraid array. An ntfs partition (the Windows NT/2000/XP filesystem), is not safely writable by Linux and thus will not work.!-->
The original persistent_home by Matthias Schwarze as well as the
knoppix home=.. feature
also belong to that category of scripts, which currently don't know
about ataraid adapters. (Thus, when scanning the harddisk partitions for
a the loopback-file conaining your home, ataraid partitions will be skipped.)
However, the version of persistent_home shipped with the plugconf package handles ataraid correctly.
Now, mount the partition on which you want to store your home directory, e.g. by clicking on the matching icon on your Desktop. Note that you cannot use a partition containing a ntfs filesystem (the format which comes with Windows NT/2000/XP) since writing to such partitions is very unsafe under Linux. You will probably lose all data on that partition if you try!!! If you only have a single big partition with NTFS you may either buy another hard disk or use one of the partitioning tools (only available from commercial suppliers, e.g. PartitionMagic from powerquest or AcronisOSselector) which can safely resize NTFS. Make the NTFS partition smaller, and add another partition, e.g. of the ext2 or FAT32 type.If your destination partition is mounted correctly run the
knx_persistent_homeprogram (or just click on the icon 'Make your HOME directory persistent'.) This program will assist you in creating an image file, in which your home directory is stored. If you are ready, you can reboot again and everything should work. However, you always must enter 'knoppix floppyconfig' at the 'boot:' prompt.
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