Adding RAID 6 support to the Installation Disk
Currently, I am using the ARC-1220 Areca raid controller with the RAID 6 engine under Debian. The system is i386 based and the only hard drives on the system is the Raid 6 drive set. This is a hardware raid solution.
I believe it would be beneficial for Etch users to have a Raid 6 installation option that really works at time of installation. I can help with testing and even do some patches. My time is limited, and I do know time is short with the upcoming planned Etch stable release. If the installation team is open for this, please contact me and let me know the best way to approach this if there is a desire to include this capability into the installation disk.
This would require an addition of a device driver with a risk factor that I believe to be low. Currently the drive is open source and has been included into the Git Tree at kernel.org. The driver is supported by the company now and complies with the
kernel code writing standards. I believe the drivers will be included in the 2.6.19 or 2.6.20 kernel.org. However, I understand that Etch will use 2.6.16 or 2.6.18 and thus the driver will not be included.
This may be one of the best Raid 6 solutions on the market at this time and it does seem to work well with Debian. Another Areca customer made a Debian install disk based on Sarge, which I have been using. It works well, but does not have the driver support for other common devices like sound that are in the newer kernels.
The install disk used the 2.6.8 kernel. I have used the manufacturer's provided drivers on kernels 2.6.8, 2.6.16 (Debian version), and 2.6.18 (kernel.org version). I used the drivers from the git Tree and personally installed the drivers in 2.6.16 deb source and 2.6.18 kernel.org source so that I could configure the drivers though make menuconfig. The drivers are installed as modules.
Both kernels seem to work fine.
Note, that the purpose of this system configuration is to be 100% RAID 6 where in such a case it would be very convenient to have RAID 6 support at time of installation. Test data so far seems to support that this may very well be possible, at least for the test hardware set under use.
Some Functional Test Results Follow:
The following outlines one of the experiments that I performed. Keep in mind that the only hard drives on the system is the RAID 6 set. I configured 4 drives using the Raid's boot bios software. Once the RAID 6 was configured, Debian was installed from CD using a modified Sarge installation disk. During the actual install, while loading the base system I randomly pulled one of the 4 drives from the system, then in a few minutes pulled another. The alarms sounded, but the install proceeded. After a few minutes I put the drives back into the system. Keep in
mind that I am proceeding with the installation without any delay while the two drives are pulled out and then put back into the system. Once the drives re-synced, I did it again and again with differing drives.
I then: 1) Added the driver to the stock 2.6.18 kernel from kernel.org, 2) With the 2.6.18 kernel loaded, did a distribution upgrade from Sarge to Etch (Testing). 3) Then modified the Debian 2.6.16 kernel source and installed. All of this work was done on the test system with the RAID 6 set as the only hard drive. I did numerous demonstrations allowing any that came by to randomly select one or two drives and pull them out at will.
The system is still in use and under test. Results are good.
Hal
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