Hopfgeist

Hopfgeist , 3 months ago

Let’s do the math:

The error-reate of modern hard disks is usually on the order of one undetectable error per 1E15 bits read, see for example the data sheet for the Seagate Exos 7E10. An 8 TB disk contains 6.4E13 (usable) bits, so when reading the whole disk you have roughly a 1 in 16 chance of an unrecoverable read error. Which is ok with zfs if all disks are working. The error-correction will detect and correct it. But during a resilver it can be a big problem.

Hopfgeist , 3 months ago

Bit error rates have barely improved since then. So the probability of an error whenr reading a substantial fraction of a disk is now higher than it was in 2013.

But as others have pointed out. RAID is not, and never was, a substitute for a backup. Its purpose is to increase availability. And if that is critical to your enterprise, these things need to be taken into account, and it may turn out that raidz1 with 8 TB disks is fine for your application, or it may not. For private use, I wouldn’t fret. but make frequent backups.

This article was not about total disk failure, but about the much more insidious undetected bit error.

Hopfgeist , 3 months ago

Then why do you think manufacturers still list these failure rates (to be sure, it is marked as a limit, not an actual rate)? I’m not being sarcastic or facetious, but genuinely curious. Do you know for certain that it doesn’t happen regularly? During a scrub, these are the kinds of errors that are quietly corrected (althouhg the scrub log would list them), as they are during normal operation (also logged).

My theory is that they are being cautious and/or perhaps don’t have any high-confidence data that is more recent.

Hopfgeist , 4 months ago

I also use this, and it works great. Another downside is that when using the free service, others can just use subdomains of your registered domains. You can always deny it, but you have to do it manually. With the premium subscriptions you can prevent that automatically for a number of domains, depending on how much you pay.

Hopfgeist , 6 months ago

To add, unlike “traditional” RAID, ZFS is also a volume manager and can have an arbitrary number of dynamic “partitions” sharing the same storage pool (literally called a “pool” in zfs). It also uses checksumming to determine if data has been corrupted. On redundant setups it will then quietly repair the corrupted parts with the redundant information while reading.

Hopfgeist , 6 months ago

mixing drive models is certainly not going to do any harm

It may, performance-wise, but usually not enough to matter for a small self-hosting servers.

Hopfgeist , 6 months ago

ebay is very international, and is also by far the greatest site for second-hand stuff in most European countries. I normally buy my used drives there.

Hopfgeist OP , 7 months ago (edited 7 months ago)

I’m not touching that post again. But a small rant about typesetting in lemmy: It seems there is no way whatsoever to put angle brackets in a “code” section. In an overzealous attempt to prevent HTML injection, everything in angle brackets is just removed when posting (although it remains there in preview). In normal text, you can use “<”, but not inside “code” segments, where it will be retained verbatim.

Hopfgeist OP , 7 months ago

Sure, SCSI disks will show their defective list (“primary defects”, as delivered by the factory, and grown defects, accumulated during use), and they all have a couple hundred primary defects. But I don’t see why that would affect the reported geometry, given that it is fictional, anway. And all disks have enough spare tracks to accommodate for the defects, and offer the specified full number of total sectors, even for long list of grown defects. Incidentally, all the 4TB disks are still “perfect” in that they have no grown defects.

And yes, ever since LBA, nobody has used sectors and cylinders for anything.

Hopfgeist , 7 months ago

RAID is generally a good thing but don’t get complacent, follow the 3-2-1 method

To expand on that: Redundant drive setup and backups serve completely different purposes. The only overlap is in case of a single disk failure, where RAID (or similar) may save the data.

Redundancy is all about reducing downtime in case of single hardware failures. Backups not only protect you from data loss in case of multiple simultaneous failures, but also from accidental deletion. Failures that require restoration of data almost always involve downtime. In short: You always need backups (unless it’s strictly a local cache, and easily recreatable), but if you want high availability, redundancy may help.

3-2-1-rule for backups, in case you’re unfamiliar: 3 copies of important data, on 2 different media, with 1 off-site.

Hopfgeist , 7 months ago

If you’re as paranoid as me about data integrity, SAS drives on a host adapter card in “Initiator Target” (IT) mode with write-cache on the disks disabled is the safest. It will degrade performance when writing many small files concurrently, but not as badly as with SATA drives (that’s for spinning disks, of course, not SSD). With a good error-correcting redundant system such as ZFS you can probably get away with enabled write cache in most cases. Until you can’t.

Hopfgeist , 7 months ago

That’s a very narrow-minded view. I thought the same thing when the iPad was new. But I changed my mind.

Sitting on the sofa and watching movies or reading news is a good application, a laptop is too clunky for that, and a phone screen is too small.

Also use as an air-navigation device (not only) light aircraft, and replacement for paper charts in airline operations. There are many legitimate uses where tablets are exactly what you want. If it’s not for you, fine.

Hopfgeist OP , 8 months ago

I’d have to check the baffle shape again. But thanks for the insight.

Hopfgeist OP , 8 months ago

It’s much more than a fan shroud. It’s a baffle specifically designed to guide cooling air over the CPU heatsinks and the RAM modules. This kind of airflow design is very common in servers. I wouldn’t trust it without, especially since the CPU heatsinks have no dedicated fans, but rely on the aerodynamic functioning of the baffle.

And yes, I know they are very similar, in fact I am quite (but not absolutely) certain that they are identical except for the actual second CPU socket. It’s almost as if you didn’t read my post. Even the soldering points for the second CPU socket are there in the single-CPU T320. They certainly won’t have different PSU connectors. They even share part numbers for the case.

Hopfgeist OP , 8 months ago

Clearly you neither read my post nor looked into what the air baffle in the T320 actually looks like. So whats your point?

Hopfgeist OP , 7 months ago

Thanks.

Hopfgeist , 9 months ago

One urgent thingis that the EU follow the UK in abandoning the ill-conceived “client-side scanning”, aka Chat-Control.

Hopfgeist , 10 months ago

MigSu-24 bombers

There’s no such thing as a MiG-24. (MiG has only ever used odd-numbered model designations, though I don’t know why. But it’s one of the reasons why it was a safe bet for Top Gun to use “MiG-28”, being sure not to refer to any real aircraft, past, present or (probably) future.

Hopfgeist , 10 months ago

Although I’m a bit late, it is worth mentioning, that the Tu-22M3 is not just a variant of the Tu-22. The Tu-22 was a completely different aircraft, and the Tu-22M retained the name only for political reasons. The Tu-22M3, though, is actually a development of the Tu-22M, most notably with different air intakes.

Hopfgeist , 11 months ago

I use the names of chemical elements, but with two twists: I assign them in the order in which they appear in the song “The Elements” by Tom Lehrer, and I use the German names. So I have (or had), among others, Wasserstoff, Sauerstoff, Stickstoff, etc …

Hopfgeist , 11 months ago

Same here. It just says “nginx has been successfully installed” or something like that. It serves the appropriate directories or redirects to the respective virtual machines for other (sub) domains.

Hopfgeist , 11 months ago

ZFS raidz1 or raidz2 on NetBSD for mass storage on rotating disks, journaled FFS on RAID1 on SSD for system disks, as NetBSD cannot really boot from zfs (yet).

ZFS because it has superior safeguards against corruption, and flexible partitioning; FFS because it is what works.

Hopfgeist , 11 months ago

What are the advantages of raid10 over zfs raidz2? It requires more disk space per usable space as soon as you have more than 4 disks, it doesn’t have zfs’s automatic checksum-based error correction, and is less resilient, in general, against multiple disk failures. In the worst case, two lost disks can mean the loss of the whole pack, whereas raidz2 can tolerate the loss of any 2 disks. Plus, with raid you still need an additional volume manager and filesystem.

Hopfgeist , 11 months ago

The Playstore says Infinite Painter won’t work on my device. What are the requirements? I have 6GB RAM and Android 13. What more could it want? Or is it generally only for tablets?

Hopfgeist , 11 months ago

The manual says it works on “any phone or tablet”, running Android 7 or higher. Mine is a OnePlus 6T running LineageOS 20 (Android 13). On my much slower and less well-equipped Samsung Galaxy Tab A7 Lite LTE (3 GB RAM) it installs just fine. Would it really object to being installed just because the phone has an unlocked bootloader? It isn’t rooted, and even banking apps work fine.

Strange. Maybe I’ll file a bug report. It looks like something I might spend $10 on if it works fine.

Hopfgeist , 11 months ago

Yes. I use a G7 N36L as an offsite-backup server in my second apartment. Works great with NetBSD and zfs, using rsnapshot to make remote backups every night.

Since it is only active for an hour and a half each night, it is my only server to put the disks into powersave mode the rest of the time. Computing eprformance is so low that I don’t even run a folding@home client. It usually cannot finish any work package before the deadline.

Hopfgeist , 11 months ago

a future where all computing/devices are locked down

And who would mandate and control such a requirement? And how would it be enforced? And why?

The only reason Apple is locked down as it is, is that Apple as the only manufacturer has absolute control over architecture, hardware and software.

Being open will always be a unique selling point by at least some competing companies, so there will continue to be some, absent a dictatorship rigorously controlling the manufacture and sale of such devices. But I think not even China has managed to accomplish that. Open devices are an absolute necessity if you want research and technological progress. And if the industry needs it, some of it will inevitably become available to citizens, too.

Hopfgeist , 11 months ago

Rooting your phone and unlocking the bootloader are separate (and mostly independent) things. E.g., by default, LineageOS is not rooted, but it requires an unlocked bootloader to install. Now, rooting without an unlocked bootloader is harder.

Hopfgeist , 11 months ago

Sounds dystopian, but I can’t find fault with your reasoning. Thanks for elaborating.

Hopfgeist , 11 months ago

For large storage, ECC helps a lot for avoiding storage corruption. In combination with a redundant architecture in zfs it is almost bullet-proof. (Make no mistake, redundant storage is no substitute for backups! You still need those.)

One option is to use comparatively old server hardware. I have some pretty old stuff (around 10 years) that uses DDR3 RAM, which is dirt cheap, even with ECC (somewhere around 1 €/GB). And it will be fast enough by far for most applications. The downside is higher power consumption for the same performance. The Dell T320 I have with eight 3.5" SAS disks and 32 GB RAM uses some 140 W of power, to give you a ballpark figure.

Hopfgeist , 11 months ago

Gold-plating the connectors is actually one of the few things that does make sense. When new, they won’t sound better, but they corrode less, which can, sometime in the future, make a difference, albeit very slight: surface oxidation can form a tiny capacitor. That said, I think you’d be hard-pressed to tell the difference to chrome-plated ones. But unlike lots of other esoteric “high-end” nonsense, this one has at least theoretical technical merit. And the micrometer-scale galvanic gold-plating isn’t expensive, either.

Hopfgeist , 11 months ago

SkyDemon (aerial navigation), Signal, Fennec (unbranded Firefox).

Hopfgeist , 11 months ago

Windy, overall, but especially for VFR forecasts, one of the few that will give cloud ceiling and visibility, and detailed winds (both on the ground and aloft, steady and gusts).

DWD Warnwetter for rain and warnings.

Hopfgeist , 11 months ago

Aside from a brief scare a couple of months ago, when the owner/operator was unreachable and the configuration interface and some automatic update paths were not working, I have been using afraid.org, and it has proven to be a stellar service, and free for basic needs.

Hopfgeist , 11 months ago

The BBC just reported that he resigned.

Hopfgeist , 11 months ago

Most of the OnePlus series, including older models, is fully supported by LineageOS, and unlocking the bootloader is straightforward. That were the most important reasons for me to go OnePlus. For me and my family there was nothing else comparably easily supported by Lineage with a good price/performance ratio. We currently use 6T and 8T models, that we bought used. The only downside for me is the lack of a notification light.

Hopfgeist , 1 year ago

I found nextcloud easier to set up than many other services, plus it comes with cloud file storage and other goodies as a bonus.

It is even easy on such obscure platforms as NetBSD in an nvmm-backed qemu virtual machine runnning on a NetBSD host.

(EDIT: well, it wasn’t really trivial, the database (PostgreSQL in my case) setup and connection is not necessarily obvious to someone who hasn’t done it before, but the fact that it works without real complications on very diverse platforms is a testament to its clean code.)