Speeding up a Synology rebuild

After purchasing a Synology NAS I inserted a bunch of drives and left ‘expanding’ overnight.

When I came back in the morning it had gone from 2% to 5% complete – about 95% less than what I was hoping.

I discovered that you can SSH into the box and check the status of the rebuild with:

cat /proc/mdstat

This showed that I had another 14 days left. Hmm, I don’t think so.

After some poking about I discovered it defaults to a strangely small 256 byte cache size.

There were a lot of posts on the internet about changing this value in /sys/block/md3/md/stripe_cache_size, but this failed with a permission problem. Maybe this applied to older versions.

Instead you can edit:


And add the line:


It took a few minutes for this to be picked up and then the rebuild time decreased to 14 hours. Much more acceptable.

I tried some larger cache size values but they didn’t make any difference.

Clearing Chrome’s DNS cache

If you ever need to point a domain name at an IP address, for sandboxing during development, or for whatever reasons, then Chrome can be a real nuisance. It seems to cache the domain name and refuses to use your new IP address.

Recent versions supposedly monitor /etc/hosts, and if you view the DNS cache this seems to be true.


However it can still be stubborn about actually using the new IP. After some digging I found that clearing the socket pool usually does the trick.


Certainly beats waiting until Chrome finally gives up the old values.

American Gods

American Gods

I’ve been very much enjoying American Gods on Amazon Prime. It’s been a few years since I read Neil Gaiman’s book, but the adaptation seems incredibly accurate to the point where I feel like I’m having flashbacks to reading it. From my understanding the first season is only a fraction of the book, so there’s plenty of time to fill the story out.

Here’s a clip from the latest episode, Lemon Scented You, in which Gillian Anderson appearing as Bowie convinces someone to change their image.

Later on, appearing as Marilyn Monroe, she blows a kiss that slices someone’s lips off. If you’ve not seen the show, or read the book, then strap in – it’s quite a ride.

Zhiyun Z1 Smooth C Gimbal

I generally don’t take much video – compared to taking photos I find it boring and laborious. Even though there’s a big red record button on my camera I just forget to press it.

After returning from a big trip last year I realised I had no video. Literally nothing at all. A year later I’m regretting that and decided I should take more. I’m not talking about making movies here, just simple home documentary videos.

One of my dislikes about home video is shakiness and so when I came across the Zhiyun gimbal it spiked my interest. After a few months of indecision I decided to get one for a vacation.

It should be noted this is a gimbal for a mobile phone, and not for a DSLR. My iPhone takes 4k video of a sufficient quality for my needs, and the gimbal itself is small and packable.

I’ve been really happy with the results. Splicing together a video from non-gimbal and gimbal footage shows such a big difference. Video is smooth and, dare I say it, cinematic. I’ve found myself watching recordings in much the same way you get sucked into watching YouTube.

It doesn’t completely eliminate vibrations, of course. Walking results in a gentle but very watchable sway.

Caveats? Sometimes you need to fight the gimbal to get it pointing in the right direction, and sometimes it can bounce between two points if you happen to keep moving between whatever threshold triggers a pan.

Overall though it’s a huge improvement for my home video and I’m sure I’ll be recording much more.

Now to figure out an easier way to edit it all together. Also maybe something for better audio.

A clockwork tortoise, a magic tree, and The Beano

A clockwork tortoise, a magic tree, and The Beano

I’m not usually one for sentimentality. Most of the things from my childhood have been thrown away, lost, or have otherwise disappeared along the way.

Saying that, while digging through boxes I came across some old books. These are books that are old enough, or memorable enough, to have survived the great Kindle purge of the early 2010s.

I thought it would be fun to show a few here.

First up is Johnny The Tin Tortoise.


Continue reading “A clockwork tortoise, a magic tree, and The Beano”

Using pv to view the progress of dd

If you use dd for any kind of copying you’ll know how it’s not exactly forthcoming with information and it’s hard to tell if it’s doing anything.

Some versions of dd have a status=progress parameter that will output progress information. Sadly this doesn’t exist on the native MacOS version.

An alternative way of showing progress information is to use pv (or pipe viewer).

First install it with brew:

brew install pv

Then wedge pv between reading from the dd source and writing to the dd output.

For example, you might write a Raspberry Pi image to an SD card with:

dd if=retropie.img of=/dev/rdisk4

Using pv you break this into the input and output parts and put pv in the middle:

dd if=retropie.img | pv | dd of=/dev/rdisk4

Sudo needs to be added to both calls to dd:

sudo dd if=retropie.img | pv | sudo dd of=/dev/rdisk4

Telling pv how much data you are transferring allows it to provide better information, and you can do this with the -s flag. In this instance the amount of data is the size of the input image, so:

sudo dd if=retropie.img | pv -s `stat -f%s retropie.img` | sudo dd of=/dev/rdisk4

And what is the result of this? You get to see the progress! Useful if you’re transferring a large amount of data.