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<p>Created page with &quot;==Notes== &lt;pre&gt; Lecture 7 --------- What is Solaris? - proprietary UNIX - although OpenSolaris was released under a copyleft license that is specifically incompatible...&quot;</p> <p><b>New page</b></p><div>==Notes==<br /> <br /> &lt;pre&gt;<br /> Lecture 7<br /> ---------<br /> <br /> What is Solaris?<br /> - proprietary UNIX<br /> - although OpenSolaris was released under a<br /> copyleft license that is specifically incompatible<br /> with the GPL (CDDL)<br /> - but then was made proprietary again<br /> - community still maintains opensolaris?<br /> <br /> - originally was the successor to SunOS, which<br /> was based on BSD UNIX (Solaris was based on System V<br /> UNIX)<br /> - Oracle got it when they bought Sun<br /> - zfs &amp; dtrace started with Solaris, now more widely used<br /> <br /> What is a container?<br /> - in the paper, zone with resource management<br /> - but in modern usage?<br /> <br /> Experience 1 is all about containers<br /> - as managed with kubernetes<br /> <br /> A container is essentially the userland of a process<br /> - containers on a host share a kernel<br /> - unlike virtual machines, where each VM has a kernel<br /> and the whole is managed by a hypervisor<br /> <br /> Kubernetes is an orchestration platform<br /> - i.e., it manages containers<br /> <br /> Containers are the unit of distribution in the cloud today<br /> (even more than virtual machines)<br /> - NOT processes<br /> <br /> So a container is...<br /> - a group of processes<br /> - and associated storage and other resources<br /> (whatever those proceses need &quot;locally&quot;)<br /> <br /> A process can&#039;t be easily isolated from the rest of the system<br /> - that&#039;s why plan9, LOCUS and such seem to forward so<br /> much towards other systems (turns into client/server)<br /> <br /> But a container is...self contained<br /> - so you can package it up, move it around, run it anywhere<br /> <br /> It is really a minimal abstraction of a host, not a process<br /> - a VM is an abstraction of a host, but with extra overhead<br /> - for 50 host-like things, why run 50 kernels when<br /> you can just run one?<br /> <br /> Solaris zones was really about the sharing of individual systems<br /> - much like OS virtualization has been used in the past<br /> - classic use case: multiple web servers on a host<br /> - really good for any app that wants &quot;a whole computer&quot; to<br /> run<br /> <br /> What&#039;s hard about containers?<br /> - security, specifically isolation<br /> - UNIX-like kernels weren&#039;t built to separate groups<br /> of processes so strictly<br /> - remains a big problem today, where best practices<br /> currently is to not run containers from multiple<br /> customers on the same system (VM)<br /> - each customer should use their own VMs because<br /> hardware virtual machines provide better isolation<br /> - so many opportunities for processes in one container<br /> to mess with other containers<br /> - because OS kernels have so many shared<br /> data structures<br /> <br /> What you should read to really understand this is your TAs master&#039;s thesis<br /> - he just defended<br /> - it is really good<br /> - bpfcontain :-)<br /> (old version, bpfbox)<br /> <br /> the cloud really took off on the basis of virtual machines<br /> - if you go to AWS and rent a &quot;computer&quot;, your renting a hardware-based VM (likely running on Linux&#039;s KVM or Windows&#039;s Hyper-V)<br /> - in this old version of Solaris, the fair share scheduler is just for the CPU<br /> - you really have to manage CPU, memory, disk, network, and any other I/O<br /> <br /> The other big change today is containers are most frequently disposable<br /> - built from an immutable disk image<br /> - easily thrown away when not needed, has no<br /> critical state (that state is stored elsewhere)<br /> &lt;/pre&gt;</div>

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