DS620slim tiny home server

In this blogpost, I describe the Synology DS620slim. Mostly these are notes for myself, so when I need to replace something in the future, I can remember how I built the system. It's a "NAS" (network attached storage) server that has six hot-swappable bays for 2.5 inch laptop drives.

That's right, laptop 2.5 inch drives. It makes this a tiny server that you can hold in your hand.

The purpose of a NAS is reliable storage. All disk drives eventually fail. If you stick a USB external drive on your desktop for backups, it'll eventually crash, losing any data on it. A failure is unlikely tomorrow, but a spinning disk will almost certainly fail some time in the next 10 years. If you want to keep things, like photos, for the rest of your life, you need to do something different.

The solution is RAID, an array of redundant disks such that when one fails (or even two), you don't lose any data. You simply buy a new disk to replace the failed one and keep going. With occasional replacements (as failures happen) it can last decades. My older NAS is 10 years old and I've replaced all Continue reading

Worth Reading: On the Dangers of Cryptocurrencies…

Bruce Schneier wrote an article on the dangers of cryptocurrencies and the uselessness of blockchain, including this gem:

From its inception, this technology has been a solution in search of a problem and has now latched onto concepts such as financial inclusion and data transparency to justify its existence, despite far better solutions to these issues already in use.

Please feel free to tell me how he’s just another individual full of misguided opinions… after all, what does he know about crypto?

Worth Reading: On the Dangers of Cryptocurrencies…

Bruce Schneier wrote an article on the dangers of cryptocurrencies and the uselessness of blockchain, including this gem:

From its inception, this technology has been a solution in search of a problem and has now latched onto concepts such as financial inclusion and data transparency to justify its existence, despite far better solutions to these issues already in use.

Please feel free to tell me how he’s just another individual full of misguided opinions… after all, what does he know about crypto?

Possible Impacts Of Covid-19 On Data Networking

This post originally appeared on the Packet Pushers’ Ignition site on April 22, 2020.   In this post I review what might happen to networking when we return to work. We won’t return to normal, but we will be back at work. To start, here are nine ideas about the pandemic’s impact, divided into two […]

The post Possible Impacts Of Covid-19 On Data Networking appeared first on Packet Pushers.

Micron ships high density SATA-based SSDs for data centers

Micron Technology is bucking the trend of moving to PCI Express-based storage and releasing a new SATA III-based SSD with ultradense memory storage and read optimized for faster data access.The SATA interface has been around since the beginning of the century, but it has progressed much slower than the PCIe interface and with nowhere near the leaps in performance. Among gamers, who are as obsessed with performance as someone doing AI models, PCIe drives are standard issue, and SATA drives are at best used for storage.That’s because SATA III has a throughput of about 550MB/s, while PCIe 4.0 has more than 10 times the throughput.To read this article in full, please click here

Micron ships high density SATA-based SSDs for data centers

Micron Technology is bucking the trend of moving to PCI Express-based storage and releasing a new SATA III-based SSD with ultradense memory storage and read optimized for faster data access.The SATA interface has been around since the beginning of the century, but it has progressed much slower than the PCIe interface and with nowhere near the leaps in performance. Among gamers, who are as obsessed with performance as someone doing AI models, PCIe drives are standard issue, and SATA drives are at best used for storage.That’s because SATA III has a throughput of about 550MB/s, while PCIe 4.0 has more than 10 times the throughput.To read this article in full, please click here

The Linux fold command breaks up text, drives loops

The Linux fold command enables you to break a string of characters into same-size chunks, but it can also be used to provide a series of characters or strings to drive a loop. This post reviews the basic command and then demonstrates how you can use it to loop through the characters or strings that it creates.The basic use of the fold command is to take long lines of text and break them into shorter pieces. One common use is to shorten lines in a text file so that they display well in a terminal window. Lines wider than the terminal width might otherwise wrap in inconvenient places.The fold command can also be used to create a narrower file from a file with lines that are inconveniently long.To read this article in full, please click here

The Linux fold command breaks up text, drives loops

The Linux fold command enables you to break a string of characters into same-size chunks, but it can also be used to provide a series of characters or strings to drive a loop. This post reviews the basic command and then demonstrates how you can use it to loop through the characters or strings that it creates.The basic use of the fold command is to take long lines of text and break them into shorter pieces. One common use is to shorten lines in a text file so that they display well in a terminal window. Lines wider than the terminal width might otherwise wrap in inconvenient places.The fold command can also be used to create a narrower file from a file with lines that are inconveniently long.To read this article in full, please click here

Juniper vQFX on GNS3

The vQFX is a virtualized version of the Juniper Networks QFX10000 Ethernet switches portfolio. It is a free tool that is not sold and therefore not supported by Juniper. The vQFX offers the same control and data plane features as the physical QFX10000 switches with limited software forwarding performance. We can use the vQFX to […]
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SR Linux in Containerlab

This article uses Containerlab to emulate a simple network and experiment with Nokia SR Linux and sFlow telemetry. Containerlab provides a convenient method of emulating network topologies and configurations before deploying into production on physical switches.

curl -O https://raw.githubusercontent.com/sflow-rt/containerlab/master/srlinux.yml

Download the Containerlab topology file.

containerlab deploy -t srlinux.yml

Deploy the topology.

docker exec -it clab-srlinux-h1 traceroute 172.16.2.2

Run traceroute on h1 to verify path to h2.

traceroute to 172.16.2.2 (172.16.2.2), 30 hops max, 46 byte packets
1 172.16.1.1 (172.16.1.1) 2.234 ms * 1.673 ms
2 172.16.2.2 (172.16.2.2) 0.944 ms 0.253 ms 0.152 ms

Results show path to h2 (172.16.2.2) via router interface (172.16.1.1).

docker exec -it clab-srlinux-switch sr_cli

Access SR Linux command line on switch.

Using configuration file(s): []
Welcome to the srlinux CLI.
Type 'help' (and press <ENTER>) if you need any help using this.
--{ + running }--[ ]--
A:switch#

SR Linux CLI describes how to use the interface.

A:switch# show system sflow status

Get status of sFlow telemetry.

-------------------------------------------------------------------------
Admin State Continue reading

Optimizing TCP for high WAN throughput while preserving low latency

Optimizing TCP for high WAN throughput while preserving low latency
Optimizing TCP for high WAN throughput while preserving low latency

Here at Cloudflare we're constantly working on improving our service. Our engineers are looking at hundreds of parameters of our traffic, making sure that we get better all the time.

One of the core numbers we keep a close eye on is HTTP request latency, which is important for many of our products. We regard latency spikes as bugs to be fixed. One example is the 2017 story of "Why does one NGINX worker take all the load?", where we optimized our TCP Accept queues to improve overall latency of TCP sockets waiting for accept().

Performance tuning is a holistic endeavor, and we monitor and continuously improve a range of other performance metrics as well, including throughput. Sometimes, tradeoffs have to be made. Such a case occurred in 2015, when a latency spike was discovered in our processing of HTTP requests. The solution at the time was to set tcp_rmem to 4 MiB, which minimizes the amount of time the kernel spends on TCP collapse processing. It was this collapse processing that was causing the latency spikes. Later in this post we discuss TCP collapse processing in more detail.

The tradeoff is that using a low value for Continue reading

Don’t let automation break change management

The drive to automate more and more network operations is a good thing, but it exposes a need for network teams to ensure their change-management processes are in order.Networks are doing more, becoming integral to zero-trust security architectures, for example, and to end-to-end enterprise optimization endeavors. Networks are also connecting more things than ever: Mobile devices and IoT nodes continue to proliferate outside data centers and IaaS environments, while inside the enterprise, VMs and containers and separate environments segregating groups of them from each other for security purposes continue to proliferate.To read this article in full, please click here