Suppose we have the Linux OS installed on two identical machines that supports the version of latest Docker. Then suppose we build a container image based on this OS. We can assume this image will now run on either machine. We now put this image onto a USB drive and plug it in the other identical machine.
Now, the hard part... is it possible, using that image on the USB drive to run the container on the same USB drive itself while plugged into the machine?
I'm trying to save and/or minimize memory used by the host OS by utilizing the memory on the USB drive as much as possible.
If this is possible, how would I go about setting up a demo case?
I see this question as "how do I persist Docker data on a USB device?".
On your machines, you need to mount your USB device into /var/docker. And then restart your Docker service.
However, with this solution, when you unplug the USB device, all of the containers have to be stopped. Otherwise, data will be lost.
Related
The following is the case and question:
I have a linux installation on a 128GB sandisk.
When I clone the disk on another 128GB sandisk the UUID stays the same.
My first thoughts to detect a clone was to check the UUID but that clearly does not work.
So my question is: How can I detect that the cloned USB is actually a clone?
Is there any way to uniquely identify the USB disk device itself given that your booting from it and not inserting it in the USB port of another linux system?
I have some python code (with PyKCS11) that reads out data from an eID smart card. The eID card is connected to the PC via an USB smart card reader. I'm trying to move this entire setup to docker on a Windows 10 host. The image used is python:slim-buster. I was able to install all the necessary drivers + other software on the image. The problem however is with the USB itself, the docker container is unable to fetch the information. I assume it's because docker is unable to detect the USB smart card reader. The same python code, when executed outside the docker container, works fine.
I've tried running docker with docker run -it --privileged MY_IMAGE_ID, but with the same issue.
Is it even possible to achieve what I'm trying to do? If so, what am I doing wrong?
I have an embedded linux device running a USB gadget kernel module to make the mmc available to the host PC(such as Windows or Linux).
When I update the file in mmc, it won't sync with host PC unless I rmmod and insmod again. Is there any better way to update new files? And how can I detect a file is modified by host PC? I'm using C programming on my linux device.
Thanks.
(1) There really isn't a better way to update new files. You need to take turns and only access the mmc from Linux or Windows, one at a time.
(2) You can't easily do that.
When you say "When I update the file in mmc", I assume that you have the mmc mounted in the linux device, and are updating files from linux at the same time that Windows has mounted the device. I don't think this is advisable. The host (Windows) may cache file and/or directory information from the mmc, and if the embedded Linux changes that information unexpectedly, it may produce errors from the Windows FS, and could corrupt the mmc.
If you want to share files between the embedded Linux and host Windows, and be able to modify them from either OS without taking turns, an alternative solution would be to use the network device gadget and run Samba file sharing on the embedded Linux side to export the filesystem where the mmc is mounted on the Linux side.
I have successfully installed RedHat Linux and run them on harddrive using VMware simulation. Things work quite smooth if I put all the nodes VM on my physical machine.
For management purposes, I want to use USB devices to store ISO and plug one if more nodes are needed. I would like to run VMware on my physical machines.
Can I just build one virtual machine on one USB device? So I can plug one node if needed.
I mean, if I simulate machine A one USB 1 and another machine B on USB 2, can I build a network using my physical machine as server?
(1) If so, are there problems I should pay attention to?
(2) If not, are there any alternative solution for my management purpose?(I do not want to make VMs on partitions of my physical machine now) Can I use multiple mobile hard drives instead?
Actually I want to start up master-slaves Hadoop2.x deployments using virtual machines. Are there any good reference for this purpose?
I shall explain that am not too lazy to have a try on my idea, however, it is now rather expensive to do so if I do not even know something about the feasibility of this solution.
Thanks for your time.
I'm not an expert on VMWare, but I know that this is common on almost any virtualization system. You can install a system :
on a physical device (a hard disk, a hard disk partition)
or on a file
The physical device way allows normally better performances since you only use one driver between the OS and the device, while the file way offer greater simplicity to add one VM.
Now for your questions :
Can I just build one virtual machine on one USB device? Yes, you can always do it on a file, and depending on host OS directly on the physical device
... can I build a network using my physical machine as server? Yes, VMWare will allow the VM to communicate with each other and/or with the host and/or with external world depending on how you configure the network interfaces of your VMs.
If so, are there problems I should pay attention to?
USB devices are pluggable and unpluggable. If you unadvertantly unplug one while the OS is active bad things could happen. That's why I advised you to use files on the hard disk to host your VMs.
memory sticks (no concern for USB disks) support a limited number of writes and generally perform poorly on writes. Never put temp filesystem of swap there but use a memory filesystem for that usage, as is done for live filesystems on read-only CD or DVD
every VMs uses memory from the host system. That is often the first limitation for the number of simultaneous VMs on a personnal system
I generally hear that LINUX OS can be downloaded on flash, pen drive (floppy disk?) etc. How we can do that?
I have RHEL 5.4 source code - so how can download it into pen drive and how much space is required?
What other functionality I can add apart from the OS - so that when I boot from that storage device I can make use of them?
Can we download Linux OS into micro-controllers also?
I generally hear that LINUX OS can be downloaded on flash, pen drive (floppy disk?) etc. How > we can do that?
If you can't get it to work on your own, you can buy a ready made Linux on a USB drive from
a site like http://www.osdisc.com or http://www.cheapbytes.com
Not all PCs, especially older PCs, can boot from the USB Drive. Even some newer PCs are beginning to ship with security features that can interfere with booting code. When it does work, you have to find out the proper way to boot the USB drive. You might have only a few seconds during reboot to enter the right key, or it will boot Windows (if Windows is installed). The key to get to the BIOS Boot Menu might be delete or escape or F10 or some other key (varies with PC motherboard manufacturer). A message on the screen that flashes by rather quickly might mention keys you can press. Boot to a specific device or changing boot order can also often be found in the BIOS setup.
There is a linux utility called unetbootin that will create a USB drive that will boot linux. It does not create a USB boot drive from a source code distribution, but rather from an ISO file representing a live CD or the live CD itself.
Since large USB drives (e.g. 32GB) are relatively inexpensive, if you want to compare systems or have multiple systems there is a way to have multiple linux and other operating systems on one USB drive and be able to choose which to boot into. See, for instance, http://www.pendrivelinux.com/ which has a wide variety of procedures for making a bootable USB using either windows or Linux to set up the USB and booting a variety of systems.
I have RHEL 5.4 source code - so how can download it into pen drive
and how much space is required?
RHEL 5.4 is a bit old. You need the Live CD, if there was one.
The ISO file can take up 600+MB. You want space left over to use the system. 2GB for the pen drive is OK. Sometimes you can get by with less.
What other functionality I can add apart from the OS - so that when I
boot from that storage device I can make use of them?
Upon boot the operating system will often recognize sound cards, other usb devices, the hard drives, etc. You need to know how to use these things within Linux, and how to enable them if they are not configured. Some Linux distributions have a place to put packages that are to be autoinstalled when a USB pen drive based system initializes. In this way you can "install" software from the distribution archives that are not included on the standard live system, even if you don't have internet access.
Can we download Linux OS into micro-controllers also?
People run it on raspberry pi and such, but the versions of Linux on non-PC hardware that has low memory are often quite tiny compared to a desktop version. They can be tiny enough to be challenging to work with or expand.