Topic: SME, EPIA motherboards, DMA and RAID

[Daniele Procida]

SME 5.6 is released with a version of the Linux kernel (2.4.18-5) under which DMA mode cannot be enabled for disk access when using an EPIA ME6000 motherboard (likely it applies to other EPIA boards).

I didn't really notice this as a problem until I installed two large (200GB) IDE disks in a server in a software RAID 1 configuration. The installation process took hours, and startup took several minutes. The machine was running extremely slowly, and constantly using the disk. After startup top revealed that the raid software was using nearly all the CPU time available. raidmonitor showed that the disk were being synchronised at a rate that would take several hours to complete.

A bit of research showed that a newer kernel would enable DMA, and greatly speed up disk access. After a couple of botched attempts to upgrade the kernel I just downloaded and installed the 6.0v3 beta, which includes version 2.4.20-18.7.

That solved all the disk problems. The installation took just a few minutes, and disk activity seems completely normal.

I hope this information is useful to someone.

Daniele

[RayG]

Thanks for the post. It's always good to have information on hardware compatability.

I use an EPIA-800 in my SME box at home. Disk access was pretty slow under SME 5.1.2 and 5.5 but 3 - 4 x faster with SME 5.6. Boot with 5.6 is almost 10x faster maybe due to the ext3 file system.

[Gareth Coleman]

yup very useful info as I am about to install sme 6.0 on a CL1000 (when the cubit case is ready!)

I am still wondering if it is worth recompiling the kernel specifically against the C3 processor? I am fairly new to Linux via IPCOP and now SME Server.

Also what performance increase can I expect if I were to add a second drive as a software RAID - adding it to the Secondary IDE channel in place of an optical drive?