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There’s one story in Twisted Presents I haven’t read here, so that’s what you get.

This isn’t a fairytale, but: Once upon a time, we were all friends.

And it’s not going to end happily ever after. On this Christmas Eve, three tedious years after the disastrous college summer when Kurt betrayed us, Phil and I are finally making an ending.
Kurt’s ill-gotten mansion looms on an isolated northern California cliff overlooking the Pacific Ocean. This deep in the night, the scents of ocean and eucalyptus rule the air. After crossing thousands of miles of open water without being soiled by filthy land animal lungs, the air is so rich that it makes me feel a little high. I deliberately focus on the basics of burglary, keeping my breath slow and placing each foot meticulously on the kitchen’s porcelain tile. Enough moonlight seeps through the fog to illuminate the mansion’s insane luxury. Had Jim died so that Kurt could have two ovens large enough to roast a calf in? Was Sarah rotting in a Turkish prison the price of a mahogany-topped island? Were the dozens of high-end cookpots dangling from the ceiling worth Danny’s awful death?

Kurt thought so.

When will Twisted Presents launch? As soon as my life is in order to allow it.

I’ve just finished prepping the print version of Twisted Presents, so here’s a tidbit from one of the stories therein.

The first Hogswatch Eve after the accident, Merle had stopped on the way back from the hospital for a fifth of Makers’ Mark. He knew if he started drinking he’d never stop, but the next day was Hogswatch and he couldn’t think of any other way to survive the night. He woke the next morning with an empty bottle, an open sewer for a mouth, and a witch’s brew in his stomach.
Through all that, he could still smell the sheets. He hadn’t changed them in weeks. There wasn’t a reason to. The bed made a warm greasy nest that suited the wreck of his life.

But it was Hogswatch. He had to get to the clinic. Soon as he could. They were reading Night Watch. For when his voice gave out, he’d loaded a couple of movies onto a tablet. White Christmas and Gremlins. He hadn’t done much in the way of shopping, but he’d picked up a fruit and nut bar at the hospital gift shop a couple days ago. It was the first treat he’d ever bought her back in college, and all the feast he could handle.

The alternative was to lie here and cry. Again. Crying always made him feel worse.

I plan to launch Twisted Presents in time for you to get your books before Christmas. Because nothing says “Happy Holidays” like curses, firearms, and orcs.

I finished the OpenZFS Mastery chapter on volumes earlier this week.

Zvols support sparse volumes, also known as thin provisioning or overcommitting storage. A sparse volume is a volume that reserves less space than the volume actually needs. Sparse volumes permit allocating more space than the pool has available. You could, for example, create ten 1-exabyte sparse volumes on your 1 TiB dataset. So long as your volumes are never heavily used, nobody will notice that you’re overcommitted. Sparse volumes can be useful if you’re prepared to add more disks. Using a sparse volume means you can tell the Windows host that a disk is a specific large size, even if the underlying pool doesn’t have that much free space.

Sparse volumes are not generally recommended. If the pool fills up but the sparse volumes think they have space remaining, writes will fail with an “out of space” error. Guests will get errors they can’t hope to resolve. Windows in particular has low distress tolerance.

I’d appreciate your support keeping the rats fed as I finish writing this book.

I’m trying to finish up the OpenZFS Mastery chapter on disk space use today. Well, my part of it. I’m planning to dump–delegate, delegate–the section on deduplication to Allan. When you have a co-author expert, use them.

Zstd offers compression levels from 1 to 19. The default is zstd-3, a reasonable compromise between performance and efficiency. Writing data at higher compression levels require more CPU but might save more space. Zstd has a useful quirk where decompressing higher levels uses no more processing power than decompressing lower levels. If you have data that must be written once but read many times, increasing the compression level makes sense.

ZFS still supports gzip compression, but Zstd is always faster and achieves better results while using less processor and memory.

ZFS also offers the ZLE algorithm, for data with long runs of zeroes. Some file formats, such as GIFs and certain scientific data, include long runs of zeroes. If you have a dataset for such data, you might find ZLE compression useful.

How does one realistically tell if your data has long runs of zeroes? The simplest way I know is to pass it across a T1 with 23 channels set to b8zs but one channel stuck on AMI. Such a circuit cannot pass large all-zero packets. Sadly, this recommendation does not suit a book on filesystems.

I would appreciate your help keeping the lights on as I finish this book.

I’m writing about space usage OpenZFS Mastery.

ZFS offers tools to transparently increase the amount of data you can fit on a disk. Rather than requiring the system administrator to compress and decompress individual files, ZFS uses efficient compression at the filesystem level. While compressing logs during rotation makes the files look smaller in ls(1), it doesn’t change how many disk blocks those logs use. Snapshots and clones let you duplicate entire datasets with only a tiny amount of space. ZFS can also perform deduplication of files, improving disk usage at the cost of memory. We’ll see how to evaluate these options and determine when to use each.

If ZFS is so transparent, why is space usage complicated? Child datasets affect their parents. Those space-efficient clones can grow, and snapshots can prevent freeing space.

I’d appreciate your help keeping the lights on while I finish this book.