Arch Linux

milomouse

Member

Registered: 2009-03-24

Posts: 940

Website

UPDATE: /dev/sdc shows up, but no such device. How to remove/reset?

UPDATE:

Please read second post for current problem, although first still applies for the most part.
Original:
=========

Sorry, I couldn't figure out a good title hopefully this is fine.

My problem: I bought a laptop with 2 hard drive bays, I bought a regular HDD and a SDD. They both showed up fine and I initially "just installed" with the regular process via ArchBoot. Everything good still. I decided I wasn't happy with the setup and was actually thinking about getting 2 SSD's instead of the regular HDD so I took out the HDD so I could do an install with just the SDD (while I wait on another SDD to arrive). This went fine, too. I put /tmp and /var/log in tmpfs, etc. But then I realized I should put /var/cache somewhere else since I do a lot of updating and custom packages very frequently. This is where the problem starts:

  1. I put in a 4GB SD Multi-Card into the little multi-card reader slot in the front. It showed up as mmblk(..) and I reformatted it as ext4. I rebooted (always like to see logs on initial boot up, etc) and the SD Multi-Card showed up as /dev/sdb instead of /dev/mmblk(..) (while the SSD was /dev/sda). I didn't think too much of it and pointed /boot and / at /dev/sda1 and /dev/sda2 while I pointed /var/cache to /dev/sdb1. Rebooted and everything seemed to work.

  2. I second guess myself and wanted to put the regular HDD back in (since it's 500GB) and I have a lot of movies/music I want to watch that will currently fill up the 240GB SSD I had ordered for the second bay (there's a small 60GB SSD for / and /boot stuff that I won't be writing to much). So I put the HDD back in, remove the SD card (since it's no longer necessary) and go through the install process again. ...  It cannot find the drive. It keeps complaining that /dev/sdb cannot be read. The logs show nothing except that it sees /dev/sdb but nothing else as with /dev/sda where it goes through identifying name, type, and attaching it.

END RESULT PROBLEM: I can put any drive (the SSD or the HDD) into any of the two hard-drive bays and only /dev/sda gets read. It shows /dev/sdb no matter what, but it cannot read medium. Everytime I boot it will show /dev/sda and /dev/sdb even if I only insert one drive into ANY bay. I try to gdisk or fdisk /dev/sdb and it says medium cannot be read. The only time I get /dev/sdb to read is when I insert that stupid SD Multi-Card. Okay, fine. So I insert both drives into both bays as well as the SD Multi-Card. It still only shows /dev/sda and /dev/sdb.. no /dev/sdc.

So, something keeps making my computer think /dev/sdb HAS to be the multi-card. I used gdisk to erase any GPT tables on every drive and clear the MBR but this still persists. I even inserted my original Windows HDD into the computer and tried reformatting every drive, hoping it would somehow fix it, to no avail--also tried to "dd" all the drives. "dd" cannot read /dev/sdb either. The drives themselves all appear to work fine, it's just that for some reason my computer WANTS /dev/sdb as the SD Multi-Card and nothing else can go there, or after it (e.g. /dev/sdc..). I see /sys/block/sdb/{files} but I KNOW there's no /dev/sdb if I only insert one drive. What the heck. :{ This folder and the /dev/sdb show up on every LiveCD I tried.

EXAMPLE ONE:
   Bay 1: SSD
   Bay 2: HDD
   MCR: <nothing>
   /dev/sda shows SSD
   /dev/sdb cannot find/read medium

EXAMPLE TWO:
   Bay 1: HDD
   Bay 2: <nothing>
   MCR: <nothing>
   /dev/sda shows HDD
   /dev/sdb still shows up, cannot find/read medium

EXAMPLE THREE:
   Bay 1: <nothing>
   Bay 2: SSD
   MCR: <nothing>
   /dev/sda shows SSD
   /dev/sdb still shows up, cannot find/read medium

EXAMPLE FIVE:
   Bay 1: HDD
   Bay 2: <nothing>
   MCR: SDMulti-Card
   /dev/sda shows HDD
   /dev/sdb shows SDMulti-Card

EXAMPLE SIX:
   Bay 1: HDD
   Bay 2: SSD
   MCR: SDMulti-Card
   /dev/sda shows HDD
   /dev/sdb shows SDMulti-Card
   SSD (/dev/sdc?) NOT shown

Did I damage the BIOs or something? Because it seems no matter what I do, it only wants /dev/sdb as the SD Multi-Card, and will not "find/read/identify" any other drive as /dev/sdb or even /dev/sd{c,d,e,...}, whereas /dev/sda can be either the SSD or the HDD just fine, but they cannot be /dev/sdb or anything else. In the BIOs boot order selection it wont show both SSD and HDD drives if theyre in there at the same time, even though it used to show both before this whole SD Multi-Card fiasco. I tried resetting BIOs but it didn't seem to do anything. I'm at a loss.

Last edited by milomouse (2010-12-24 22:47:25)

milomouse

Member

Registered: 2009-03-24

Posts: 940

Website

Re: UPDATE: /dev/sdc shows up, but no such device. How to remove/reset?

Original: 12-22-10. Today: 12-24-10. UPDATE:

So, by swapping the drives repeatedly and rebooting with the ArchBoot disc, using a combination of the Windows HDD, the empty HDD and the empty SSD in different positions (all conceivable), I was able to get Linux to "softreset" the devices so that I can FINALLY have both the empty HDD and the empty SSD read/identified at the same time, but only with the HDD in /dev/sda and the SSD in /dev/sdb (while that stupid SD Multi-Card slot keeps showing up, but this time as /dev/sdc). I think Linux is now confused and thinks that the SSD is a flash/SD device or something and therefore can't put it in /dev/sda anymore (after the SD card messed everything up). I guess everything is fine unless I have to switch devices for some reason or possibly have 2 SSDs where one wont read because of this.. We'll see.

My question now: is there any way to REMOVE a device? More specifically, I see /sys/block/sdc/{files} but there is obviously no device and I can't forcefully delete them with "rm -fr" -- I don't know another way. Can I set a udev rule or something to ignore it or possibly/preferably remove it so I can plug in another device later to be read as /dev/sdc instead of skipping to /dev/sdd? This would be great.

Edit:  I can do:   

echo 1 > /sys/block/sdc/device/delete

and it will delete for that session. But as soon as I reboot it's back. Any ideas? Udev?

Last edited by milomouse (2010-12-24 23:30:11)

tvale

Member

From: Portugal

Registered: 2008-12-11

Posts: 175

Re: UPDATE: /dev/sdc shows up, but no such device. How to remove/reset?

A /dev/sdb also appeared to me recently, but I don't really have a second hard drive. Should be the same problem!...

milomouse

Member

Registered: 2009-03-24

Posts: 940

Website

Re: UPDATE: /dev/sdc shows up, but no such device. How to remove/reset?

Could be. Mine only appeared after I previously used an SD Card (at the time, /dev/mmblk..something) and after it restarted it was called /dev/sdb and now it always shows up even if the SD Card is not there. This causes problems with my Solid State Drive being read properly but I have it sort of working right now if I don't change any positioning around. It's really bothering me though that things aren't working properly anymore. I've somehow screwed up a brand new (and expensive) laptop. It works but is now becoming very hackish to do so. Oh well.

Still no ideas on how to reassign a device or remove it permanently (preferably reassign)? Hoping someone with some hardware experience would pipe up as I'm not too familiar with the inner workings as such. On the plus side I'm learning a lot more than I normally would.

Edit: I remember upon rebooting with the SD Card after installation it said "irq changed" and did "1st FIBS failed" or something like that, which it said 3 times before doing the "softreset" and assigning the drive as /dev/sdb. There was nothing in the logs about this but I saw it during boot up. Had I of known it might have been important I would've wrote it down at the time.

Last edited by milomouse (2010-12-27 18:02:29)