Guys, this is a bit of a long one so apologies in advance.

To skip the boring into, jump straight to QUESTION

I’ve used Slackware for a number of years, mostly from 9.1, for both personal and recently some real world commercial use but this is the first time I have come across a machine that is running Slackware NOT installed and setup by me.

I’ve recently changed jobs and in my new position, I am responsabile for a number of production machines and equipment, nothing new there except for the fact that two of the machines are running Slackware 8.1
These are Production Process Machines that are running a piece of software that interfaces with a PLC and controls and displays process parameters, now at this time (only been there a week) I’m not so sure to what extent this machine it utilised but it is central to the operation of the production equipment to which it is connected.

I’ve had a quick snoop and so far, it runs Slackware 8.1, boots into a desktop enviroment (very minimal) and obviously has links to the custom controlling software installed. It’s a 2.4.* kernel showing a date of 2001 has one drive /dev/hda1

There are however a few things annoying me, so lets move on to my questions below;



########## QUESTION ##########


1 The machine shows /dev/hda/1 but I have physically seen that it is a SATA drive installed, how can this be?

2 If there was a way to change the reference from /dev/hda1 to /dev/sda1 (as it probably should be), then I’m assuming this would probably break the system, hence anyhting that references /dev/hda1 would fail. A simple example would be /etc/fstab if this contains an entry and the root xdrive was to be changed from hda1 to sda1 would this automatically update?

3 Slackware 8.1 2.4.* kernel SATA support, I thought SATA support came with 2.6.*? so I’m a little confused here, probably added to by the fact that it shoes hda1 with a connected SATA drive.

4 Opinions on best way to backup this machine so that it can be restored onto new hardware and my worry here is that it will be new hardware that probably wont work on 8.1

5 Load Average shows 35.00 35.00 35.00 never changes, any thoughts?



########## QUESTION END ##########




As the weeks pass, I’ll be much more involved with this setup and will likely post updates as I find them, so if interested check back, I am certainly excited to find what I consider a rare and interesting find. Its one thing to setup and work on youor own slackware or any kind of Linux enviroment and another to do it in a commercial or real world enviroment, I myself have done both to varying degrees but this is certainly the first that I have found something like this.

Thanks for reading and look forward to comments and help as always.

Nice find! I am responding mostly to follow the adventure but not much to contribute.

I wouldn't have known, but according to this wikipedia article SATA Rev. 1.0 was introduced in January 2003. If it was installed by someone from a familiar CD within two years after Slackware version release, that would be pretty reasonable. If it was an in house project they may have started their project when 8.1 was barnd new and simply installed this one from their own repo.

It is also possible that the disk was cloned to an SATA drive on a newer main board at a later date and the kernel simply sees the drive interface without knowing or caring whether it is (S/P)ATA that is kind of the point of the ATA part as I recall. (I am not actually sure how that would work, but I do believe that the kernel would not care). The designation hda vs sda is an entirely arbitrary kernel thing at that level. So if the kernel sees an interface it can read and identify as a disk, it would have been happy to call it hda, knowing nothing of the future designations. There would also not be any reason to change it to sda while still running the older kernel, and it would not automatically update fstab.

It might be interesting to look for date codes on the main board and the SATA drive.

*** EDIT

Just looked, Slackware 8.1 was released June 2002, so SATA hardware was out within about 6 months, not a big stretch. But still, if that is the original drive and main board in what I take to be an industrial environment that makes it 12 years old. Not unheard of but I would guess that the hardware was replaced at some point and the drive was cloned or maybe reinstalled by the in house maintainer (something I might have done!).

It's been years since I saw hda change to sda for SATA, and IIRC it's either what it says in the page at the URL below, or it's combined with Linux switching from using the IDE to SCSI drivers for SATA drives.

http://www.cyberciti.biz/faq/linux-s...ayed-as-devhda

It's meant to be like this, so you should leave it. You may even find that if you installed the latest Slackware on to this machine without changing the BIOS settings, that it switches to 'sda'. As I said, it depends exactly why it switched - whether it's exclusively due to BIOS settings or Linux internals.

One way is to rsync everything apart from /proc , /lost+found, /dev , /tmp, /var/tmp and any other stuff related to the running system.
For old software that cannot easily or realistically be updated to run on a newer platform, people often put them inside VM's.
If there are no special kernel drivers for any hardware connected to that system, you might be able to boot Slackware 8.1 installer in a VM, partition and make filesystems, then rsync the content on to the drives.
You can manually unpack the devs package to populate /dev, mkdir /proc, /tmp, /var/tmp and anything else you excluded during the backup.

About question (1): old computers may have had their BIOS settings modified so that Serial ATA drives were exposed as Parallel ATA drives. The Linux kernel would then name the drive /dev/hda . I looked at the kernel .config file for Slackware 8.1 and did not see any reference to parallel ATA there, I do not know if SATA support existed at the time?

About question (2): There is a Slackware-oriented write-up on how to make the switch from hda to sda at http://alien.slackbook.org/blog/robb...tchover-howto/

About question (4): you can try copying the whole drive to new hardware, just to see what works and what not. What are the chances of finding out whether the software that runs on this machine, will work on a more recent Slackware (or perhaps a new version of the industrial software is available?). Mozes mentioned a virtual machine, but I do not know how that will work out with access to the machine's peripherals. What you could explore is setting up a new computer with the latest Slackware, copy the old machine to a subdirectory on the new computer, and create a LXC container where you should be able to expose your PLC to the container. LXC is a "light-weight virtualization" which may be more appropriate than using VMWare, VirtualBox or QEMU.

Eric

1 members found this post helpful.

Just curious, but what is the interface to the PLC? On equipment from that period it may well be serial RS232. This can still be supported, but it may require adding a card to a new machine. You would also need to make the /etc/rc.d/rc.serial script executable in a recent Slackware release, a change from the default in earlier Slackware releases.

Hi,

If it's not broke then don't fix it! Age of the machine may require replacement but until then I would suggest to backup first to allow recovery. If the need arises then updating replacement hardware would be the way to go to keep operations the same. Nothing wrong with Slackware 8.1 especially if the systems are isolated with no chance of intrusions.

Personally, I would setup up a recovery plan in case of hardware failures. Be sure to take a hardware inventory of this system. Motherboards caps can age overtime and cause board failures. PSU is another point of potential failure. HDD could be an issue. Do you have spares for the hardware in case of a problem? What about the PLC replacement spare? Do you have system backups? Does the system have regular maintenance schedules? Industrial environments can be dirty & misting can cause issues if the system is in the dirty environment. If the PC is not in a Positive environment chamber then you will be certain to have issues over time.

I would suspect that intercommunication would be RS-485 not RS-232. RS-485 is differential and would be ideal in a production (noisy) environment. Most PLC in that circa did use RS-485 for intercommunication with controllers. TP RS-232 did provide some cancellation of noise but not anywhere near RS-485 long line.
Just some thoughts from a user that performed duties in dirty environments using PC & PLC equipment.

Hope this helps.

I'll try and find out more infomation tommorrow, certainly wont be planning on replacing but would be nice to have some comfort in a reliable backup solution.

Stay tuned...

is the sata controller on-board or an add on? if it is on-board then the hardware has probably been upgraded at some point. either way the sata controller is probably in "ide" or "legacy" mode and so the system thinks it is an ide drive.

as far as hd*/sd* like others have said if ain't broke don't fix it.

for back up if at all possible make a complete disk image that way you can just image a new drive and throw it in place if the hdd dies. I also like the idea of copying the files to a vm to test on newer versions of slackware.