Arch Linux

Xaero252

Member

Registered: 2011-11-28

Posts: 107

Installing to PCI-E SD Reader

Hello, I am looking to install ArchLinux on a 128gb SD card for use on my Clevo W110ER. However, I know that the device requires a driver to be able to access it, even under Linux. My question is, how would I go about installing to/booting from the device since the kernel alone cannot see it? Is it possible to load the driver on the fly? The bios doesn't see the device so I know I will at least have to have /boot/ on the internal disk, but I would like the remainder of the OS on the SD card if possible.

This is the card reader software:
http://www.realtek.com/Downloads/downlo … wn=false#2

Pancake_Palace

Member

Registered: 2012-07-27

Posts: 21

Re: Installing to PCI-E SD Reader

Is the driver in your kernel, and in your iinit ramdisk? If you can compile it right into the kernel, that would be ideal. Otherwise, make sure it is in the list of modules to load at boot, so that it gets put in the initial ramdisk.
https://wiki.archlinux.org/index.php/Mkinitcpio

In theory, once your initramfs is made right, you can just move / to the SD card. But, assuming it isn't that simple, you could install the OS to the disk, and then start moving directories' contents, and then directing fstab to the new location. Fstab can mount subdirectories, and I don't think you need to mount the parent partition, these days, but if it gives you trouble, mount the whole thing under /mnt or somewhere on a line before the subdirs. I would move /etc, /sbin, and /bin last.

Once it all works like that, you could start experimenting with how close you can actually get to only having /boot on the spinning drive. You should be able to get all the way there, but when I needed to do it a few years ago, in Slackware, while it was possible, it took more work than I expected it to. Arch might be easier, but it might not be. On the bright side, I do recall most errors being easy to find out about and fix, though I don't recall their details.

Finally, if you use swap, I would highly recommend not putting that on the SD. SD cards are made to cheap (in a relative sense), and the kind of load swap puts on them will not only be likely slower than the HDD (assuming you have the 7200 RPM Caviar), but will certainly cause very high wear, possibly enough to worry about killing the card from too much writing. Most SD cards do not have controllers like new SSDs do, that can keep write amplification in check for random writes, nor efficiently handle queuing for random reads.