I will keep this short and sweet. We have servers in our environment that have multiple IP addresses assigned to a single NIC. That’s normally just fine. However on occasion I will have very strange issues occur where essentially all networking appears to be working and yet web browsing won’t work. I can ping my default gateway, ping other systems in the same subnet, telnet out on port 80 and 443, etc, etc. But the network connectivity still behaves oddly. What’s the issue?
It all has to do with networking logic decisions made many years ago (I believe as far back as Windows Server 2000) by someone at Microsoft. (more…)
This lovely item came across my feed today and I realized there is so much that I do poorly when it comes to shell scripting it is absurd 🙁
Anyhow I am extremely thankful for this long and detailed post and wanted to pass it along to my readership.
I also wanted to crowd-source a bit of information from you all.
I am familiar with the idea of a code repository but have never really used one. I have had a lot of people suggest I use GIT. I am curious if that is the general consensus or if anyone else has other suggestions? I have a project that consists of some pretty crazy scripts (well, crazy for me, 1000+ lines). Trying to keep track of versions and changes in a script that large is difficult to say the least. I am looking for something easy to use and quick to deploy. Thoughts welcome.
A little over six months ago I started researching the quickly emerging world of “Hyper-converged” infrastructure as a new IT ethos to take my company’s IT operations into the next decade of application and data hosting. I was first introduced to the idea when I attended a webinar from Simplivity, one of the leading companies in this new market. I was immediately intrigued… the underlying question that Hyper-convergence answers is “What happens if you radically simplify the data-center by collapsing storage and compute into one all-encompassing platform?
The broader idea of convergence has been around for a while. I started seeing it with the advent of wider 10 Gbe adoption; the idea of taking a single (or +1 for redundancy) high-speed LAN connection and splitting up into multiple logically separate connections. I.E. you could “converge” management, application, and storage LAN connections down into a single wire. The wider over-arching concept predates even this.
Expand that thought into the virtualization space. Virtualization has been around for a very long time but traditionally if you wanted to get some kind of fault-tolerant system setup it required a complex stack of centralized network attached storage, management software, and a clustered hypervisor. Not to mention (often) separate networking equipment for both the storage and hypervisor nodes.
The promise of hyper-convergence is that many of those disparate parts can go away and instead you can host your workloads on a unified, easily scaled, inherently redundant, platform that encompasses all of your storage and compute needs while simplifying a majority of your networking. Wikipedia sums it up nicely. Rather than reinventing the wheel I will just refer you there if this is a new concept: https://en.wikipedia.org/wiki/Hyper-converged_infrastructure
Hyper-convergence is a rather elegant answer, especially if the product is designed from the outset to BE a hyper-converged platform. My premise in this article is that Scale Computing is one of the few (perhaps the only?) “proven” vendors that have developed a product from the ground up as a hyper-converged system. Based on a lot of the FUD I came across while researching, I got the distinct impression that a large number of people don’t understand this fundamental difference between Scale and the majority of other HCI products currently populating the market. This is a long post, get coffee now… (more…)
Making use of a SAN (storage area network) provides some incredible benefits. I won’t go into depth but at a high-level you often get:
1. Excellent hardware redundancy for data storage, more-so if you are using multiple arrays but even most enterprise single arrays can provide N+1 redundancy. Now we can tolerate power failures, and drive failures, and switch failures, etc…
2. Extra options for historical data integrity/backup/dr – Most enterprise SAN’s support features for volume snapshots and rollbacks. Some even support advanced features specific to protecting MS-SQL and I am sure other database products. Our implementation also provides some great options for DR, like being able to replicate data/volumes from a production SAN over to a different SAN in a different network/datacenter.
3. Administrative ease… managing storage volumes for all of your systems from one interface makes life much easier.
4. Online disk resizing — did your database run out of disk space? You have plenty of space available on your SAN though on which the volume is hosted? No problem, just increase the size of the volume on the SAN (often something you can do while the volume is online and being used) and then increase the partition in windows to take up the new volume space (also an online operation).
For these reasons (and I am sure many many more), SAN’s have become a staple in a lot of enterprise networks. But let me talk about some pain points, particularly in older SAN implementations and particularly around iSCSI and older networks.
Apparently a handful of customers using Cloudflare for DNS, and specifically CNAME records experienced a brief outage of name resolution services on New Year’s. I found the reason why to be rather interesting. Devs at cloudflare assumed time can’t move backwards… An understandable assumption but actually faulty because of leap seconds… Anyhow, if you do programming you might find the root cause analysis for this hiccup to be interesting and informative:
Well worth a quick read. No, unfortunately it didn’t have anything to do with Dark Matter and/or what happens were a black hole and a Delorian traveling at 88 mph suddenly to meet while Superman flies around the planet at light speed. But, it is still curious enough all the same. Happy New Year… Sanitize your outputs…