• I never said anything about EFI not supporting multi boot. I said that the had to be kept in lockstep during updates. I recognize the term “manual” might have been a bit of a misnomer there, since I included systems where the admin has to take action to enable replication. ESXi (my main hardware OS for now) doesn’t even have software RAID for single-server datastores (only vSAN). Windows and Linux both can do it, but its a non-default manual process of splicing the drives together with no apparent automatic replacement mechanism - full manual admin intervention. With a hardware RAID, you just have to plop the new disk in and it splices the drive back into the array automatically (if the drive matches)
  • “EFI doesn’t understand (normal) MD RAID” - https://unix.stackexchange.com/a/742072/34724 (2023)
  • (untested) “Using metadata 1.0 (end of disk) to splice EFI partitions together” - https://std.rocks/gnulinux_mdadm_uefi.html
  • (untested) “splicing windows dynamic disks together” - https://learn.microsoft.com/en-us/troubleshoot/windows-server/backup-and-storage/set-up-dynamic-boot-partition-mirroring
• Dell and HPe both have had RAM caching for reads and writes since at least 2011. That’s why the controllers have batteries :)
  • also, I said it only had to handle the boot disk. Plus you’re ignoring the fact that all modern filesystems will do page caching in the background regardless of the presence of hardware cache. That’s not unique to ZFS, Windows and Linux both do it.
• mdadm and hardware RAID offer the same level of block consistency validation to my current understanding- you’d need filesystem-level checksumming no matter what, and as both mdadm and hardware RAID are both filesystem agnostic, they will almost equally support the same filesystem-level features (Synology implements BTRFS on top of mdadm - I saw a small note somewhere that they had their implementation request block rebuild from mdadm if btrfs detected issues, but I have been unable to verify this claim so I do not consider it (yet) as part of my hardware vs md comparison)

Hardware RAID just works, and for many, that’s good enough. In more advanced systems, all its got to handle is a boot partition, and if you’re doing your job as a sysadmin there’s zero important data in there that can’t be easily rebuilt or restored.

I never said I didn’t use software RAID, I just wanted to add information about hardware RAID controllers. Maybe I’m blind, but I’ve never seen a good implementation of software RAID for the EFI partition or boot sector. During boot, most systems I’ve seen will try to always access one partition directly and a second in order, which is bypassing the concept of a RAID, so the two would need to be kept manually in sync during updates.

Because of that, there’s one notable place where I won’t - I always use hardware RAID for at minimum the boot disk because Dell firmware natively understands everything about it from a detect/boot/replace perspective. Or doesn’t see anything at all in a good way. All four of my primary servers have a boot disk on either a Startech RAID card similar to a Dell BOSS or have an array to boot off of directly on the PERC. It’s only enough space to store the core OS.

Other than that, at home all my other physical devices are hypervisors (VMware ESXi for now until I can plot a migration), dedicated appliance devices (Synology DSM uses mdadm), or don’t have a redundant disks (my firewall - backed up to git, and my NUC Proxmox box, both firewalls and the PVE are all running ZFS for features).

Three of my four ESXi servers run vSAN, which is like Ceph and replaces RAID. Like Ceph and ZFS, it requires using an HBA or passthrough disks for full performance. The last one is my standalone server. Notably, ESXi does not support any software RAID natively that isn’t vSAN, so both of the standalone server’s arrays are hardware RAID.

When it comes time to replace that Synology it’s going to be on TrueNAS

For recovering hardware RAID: most guaranteed success is going to be a compatible controller with a similar enough firmware version. You might be able to find software that can stitch images back together, but that’s a long shot and requires a ton of disk space (which you might not have if it’s your biggest server)

I’ve used dozens of LSI-based RAID controllers in Dell servers (of both PERC and LSI name brand) for both work and homelab, and they usually recover the old array to the new controller pretty well, and also generally have a much lower failure rate than the drives themselves (I find myself replacing the cache battery more often than the controller itself)

Only twice out of the handful of times I went to a RAID controller from a different generation

• first time from a mobi failed R815 (PERC H700) physically moving the disks to an R820 (PERC H710, might’ve been an H710P) and they were able to foreign import easily
• Second time on homelab I went from an H710 mini mono to an H730P full size in the same chassis (don’t do that, it was a bad idea), but aside from iDRAC being very pissed off, the card ran for years with the same RAID-1 array imported.

As others have pointed out, this is where backups come into play. If you have to replace the server with one from a different generation, you run the risk that the drives won’t import. At that point, you’d have to sanitize the super block of the array and re-initialize it as a new array, then restore from backup. Now, the array might be just fine and you never notice a difference (like my users that had to replace a failed R815 with an 820), but the result pattern is really to the extremes of work or fault with no in between.

Standalone RAID controllers are usually pretty resilient and fail less often than disks, but they are very much NOT infallible as you are correct to assess. The advantage to software systems like mdadm, ZFS, and Ceph is that it removed the precise hardware compatibility requirements, but by no means does it remove the software compatible requirements - you’ll still have to do your research and make sure the new version is compatible with the old format, or make sure it’s the same version.

All that’s said, I don’t trust embedded motherboard RAIDs to the same degree that I trust standalone controllers. A friend of mine about 8-10 years ago ran a RAID-0 on a laptop that got it’s super block borked when we tried to firmware update the SSDs - stopped detecting the array at all. We did manage to recover data, but it needed multiple times the raw amount of storage to do so.

• we made byte images of both disks in ddrescue to a server that had enough spare disk space
• found a software package that could stitch together images with broken super blocks if we knew the order the disks were in (we did), which wrote a new byte images back to the server
• copied the result again and turned it into a KVM VM to network attach and copy the data off (we could have loop mounted the disk to an SMB share and been done, but it was more fun and rewarding to boot the recovered OS afterwards as kind of a TAKE THAT LENOVO…we were younger)
• took in total a bit over 3TB to recover the 2x500GB disks to a usable state - and took about a week of combined machine and human time to engineer and cook, during which my friend opted to rebuild his laptop clean after we had images captured - to one disk windows, one disk Linux, not RAID-0 this time :P

Tbh this is a programming community. While yes, a quick summary would not have gone amiss, I don’t fault OP for not including it. RFCs are often pretty dry but this one is reasonably straightforward as a subset of JSON to reduce some ambiguity.

Yup. My background is computer science transitioned to IT Infra.

My sister sent me a screenshot of a Spotify one-liner error, white text on black background, captioned “they wrote a lazy error”. I immediately recognized that the actual problem was the load balancer in the front end trying and failing to connect to the backend/middleware in the first error, then in the second it recognized a failed health check and reporting that no back ends were available. Root cause is probably networking issue or actual server crash.

I also have a bonus that in high school I had watched a ton of videos on VFX/SFX and knew a rough way around After Effects and compositing (before I jumped into CS I had considered this as a career path), so now when I watch TV and movies I can also see some of the “layers” they use to compile the on screen effect.

Memory unlocked that’s been a hot minute ago

Didn’t apple used to make their own IR remote for that? Is the hardware onboard the Mini preset to use their hardware or is it more generic once Linux is installed?

Others have some good information here - all I’d like to add to the root is that Windows and Mac have a built-in DNS cache and it’s pretty straightforward to add a DNS cache to systemd distros (if it’s not already installed or in use) using systemd-resolved or dnsmasq if you really dislike systemd. Some distros enable this from install time.

Systems that utilize a DNS cache will keep copies of DNS query results for a period of time, making the application-level name lookup speed essentially 0ms for a cached result. Cold results obviously incur the latency of the DNS server itself.

HLS is a bidirectional protocol though - the system’s total network latency affects how quickly it can change to a new bitrate stream as conditions improve or degrade. And despite the name, it’s not just limited to live content. You can use this to deliver fixed-length content

https://en.wikipedia.org/wiki/HTTP_Live_Streaming

I’d put the deflate algorithm over the LZMA algorithm just because deflate is used by both windows (zip) and Unix (gzip). Windows I don’t think has added LZMA/xz support until recently if at all.

https://xkcd.com/2347/

Not on a flash based motherboard (so basically almost everything recent). On modern systems usually the only thing the battery powers is the clock, which is why they have a separate reset to defaults header/button/switch.

(The CMOS memory of old is replaced with flash memory, al la SD Card or flash drive)

TLDR: probably a lot of people continue using the thing that they know if it just works as long as it works well enough not to be a bother.

Many many years ago when I learned, I think the only ones I found were Apache and IIS. I had a Mac at the time which came pre installed with Apache2, so I learned Apache2 and got okay at it. While by release dates Nginx and HAProxy most definitely existed, I don’t think I came across either in my research. I don’t have any notes from the time because I didn’t take any because I was in high school.

When I started Linux things, I kept using Apache for a while because I knew it. Found Nginx, learned it in a snap because the config is more natural language and hierarchical than Apache’s XMLish monstrosity. Then for the next decade I kept using Nginx whenever I needed a webserver fast because I knew it would work with minimal tinkering.

Now, as of a few years ago, I knew that haproxy, caddy, and traefik all existed. I even tried out Caddy on my homelab reverse proxy server (which has about a dozen applications routed through it), and the first few sites were easy - just let the auto-LetsEncrypt do its job - but once I got to the sites that needed manual TLS (I have both an internal CA and utilize Cloudflare’ origin HTTPS cert), and other special config, Caddy started becoming as cumbersome as my Nginx conf.d directory. At the time, I also didn’t have a way to get software updates easily on my then-CentOS 7 server, so Caddy was okay-enough, but it was back to Nginx with me because it was comparatively easier to manage.

HAProxy is something I’ve added to my repertoire more recently. It took me quite a while and lots of trial and error to figure out the config syntax which is quite different from anything I’d used before (except maybe kinda like Squid, which I had learned not a year prior…), but once it clicked, it clicked. Now I have an internal high availability (+keepalived) load balancer than can handle so many backend servers and do wildcard TLS termination and validate backend TLS certs. I even got LDAP and LDAPS load balancing to AD working on that for services like Gitea that don’t behave well when there’s more than one LDAPS backend server.

So, at some point I’ll get around to converting that everything reverse proxy to HAProxy. But I’ll probably need to deploy another VM or two because the existing one also has a static web server and I’ve been meaning to break up that server’s roles anyways (long ago, it was my everything server before I used VMs).

A static PNG tile database for world.osm is even larger. Without a solid vector tile solution, this is the most efficient data format for disk space.

Also, there’s a post render CDN cache in front of the rendering layer to offset load, plus there’s I think some internal caching in renderd. It’s a pretty complex machine, but databases of the world are in fact huge.

OSM’s core tile servers have dozens of cores, hundreds of GB of RAM each, and the rendering and lookup databases are a few TB. That’s not trivial to self host, especially since one self hosted tile server cannot always keep up with a user flick scrolling.

Edit: car GPS maps and the old TomTom and Garmin devices have significantly less metadata embedded than a modern map.

deleted by creator

A well managed server won’t init an arbitrary drive and has a lock screen with a password so that the most a rubber ducky would be able to do is reboot it. Which is something you’d already be able to do if you had access to the front panel with the power button.

You may not but your phone will fail over to data if it loses its lease and stuff like background update tasks will cease to function (like Windows Update or dnf cron)

On/off:
I have 5 main chassis excluding desktops. Prod cluster is all flash, standalone host has one flash array, one spinning rust array, NAS is all spinning rust. I have a big enough server disk array that spinning it up is actually a power sink and the Dell firmware takes a looong time to get all the drives up on reboot.

TLDR: Not off as a matter of day/night, off as a matter of summer/winter for heat.

Winter: all on

Summer:

• prod cluster on (3x vSAN - it gets really angry if it doesn’t have cluster consistency)
• NAS on
• standalone server off, except to test ESXi patches and when vCenter reboots cause it to be WoL’d (vpxd sends a wake to all stand by hosts on program init)
• main desktop on
• alt desktops off

VMs are a different story. Normally I just turn them on and off as needed regardless of season, though I will typically turn off more of my “optional” VMs to reduce summer workload in addition to powering off the one server. Rough goal is to reduce thermal load as to not kill my AC as quickly which is probably running above its duty cycle to keep up. Physical wise, these servers are virtualized so this on/off load doesn’t cycle the array.

Because all four of my main servers are the same hypervisor (for now, VMware ESXi), VMs can move among the prod cluster to balance load autonomously, and I can move VMs on or off the standalone host by drag-and-drop. When the standalone host is off, I usually move turn it’s VMs off and move them onto the prod cluster so I don’t get daily “backup failure” emails from the NAS.

UPS: Power in my area is pretty stable, but has a few phase hiccups in the summer. (I know it’s a phase hiccup because I mapped out which wall plus are on which phase, confirmed with a multimeter than I’m on two legs of a 3-phase grid hand-off, and watched which devices blip off during an event) For something like a light that will just flicker or a laptop/phone charger that has a high capacitance, such blips are a non issue. Smaller ones can even be eaten by the massive power supplies my Dell servers have. But, my Cisco switches are a bit sensitive to it and tend to sing me the song of their people when the power flickers - aka fan speed 100% boot up whining. Larger blips will also boop the Dell servers, but I don’t usually see breaks more than 3-5m.

Current UPS setup is:

• rack split into A/B power feeds, with servers plugged into both and every other one flipped A or B as it’s primary
• single plug devices (like NAS) plugged into just one
• “common purpose” devices on the same power feed (ex: my primary firewall, primary switches, and my NAS for backups are on feed A, but my backup disks and my secondary switches are on feed B)
• one 1500VA UPS per feed (two total) - aggregate usage is 600-800w
• one 1500VA desktop UPS handling my main tower, one monitor, and my PS5 (which gets unreasonably upset about losing power, so it gets the battery backup)

With all that setup, the gauges in the front of the 3 UPSes all show roughly 15-20m run time in summer, and 20-25m in winter. I know one may be lower than displayed because it’s battery is older, but even if it fails and dumps it’s redundant load onto the main newer UPS I’ll still have 7-10m of battery at worst case and that’s all I really need to weather most power related issues at my location.

/j hey some of us only have 10GbE

Jokes aside, I get the classification. I’m pretty solidly in the category of 2c - more tech than some medium business but without the SLA to go with it.

Apologies for being late, I wanted to be as correct as I could be.

So, straight to the point: Nextcloud by default uses plain files if you don’t configure the primary storage to be an S3/object store. As far as I can tell, this is not automatic and is an intentional change at system creation by the original admin. There is a third-party migration script, but there does not appear to be a first-party method of converting between the two. That’s very good news for you! (I think/hope)

My instance was set up as a standalone, so I cannot speak for the all-in-one image. Poking around the root data directory (datadirectory in the config.php), I was able to locate my user account by internal username - which if you do not use LDAP will be the shortened login name. On default LDAP configs, this internal username may be a GUID, but that can be changed during the LDAP enablement process by overriding the Internal Username field in the Expert LDAP settings.

Once in the user’s home folder in the root data directory, my subdirectory options are cache, files, files_trashbin, files_versions, uploads.

• files contains the “live” structure of how I perceive my Nextcloud home folder in the Web UI and the Nextcloud Desktop sync engine
• files_trashbin is an unstructured data folder containing every file that was deleted by this user and kept per the trash folder’s retention policy (this can be configured at the site level). Files retain their original name, but have a suffix added which takes the form .d######... where the numbers appear to be a Unix timestamp, likely the deletion date. A quick scan of these with the file command in Linux showed that each one had an expected file header based on its extension (i.e., a .png showed as a PNG image with an expected resolution). In the Web UI, there is metadata about which folder the file originally resided in, but I was not able to quickly identify this in the file structure. I believe this info is coming in from the SQL database.
• files_version are how Nextcloud is storing its file version history (if enabled). Old versions are cleaned up per a set of default behaviors to keep more copies of more recent changes, up to a maximum age deletion threshold set at the site level. This folder is stored in approximately the same structure as the main files live structure, however each copy of each version is appended a suffix .v######... where the number appears to be the Unix timestamp the version was taken (*I have not verified that this exactly matches what the UI shows, nor have I read the source code that generates this). I’ve spot checked via the Linux file command and sha256 that the files in this versions structure appear to be real data - tested one Excel doc and one plain text doc.

I think that should get a fairly rough answer to your original question, but if I left something out you’re curious about, let me know.

Finally, I wanted to thank you for making me actually take a look at how I had decided to configure and back up my Nextcloud instance and ngl it was kind of a mess. The trash bin and versions can both get out of hand if you have frequently changing or deleting/recreating files (I have network synchronization glued onto some of my games that do not have good remote save support). Retention policy on trash and versions cleaned up extraneous data a lot, as only one of those was partially configured.

I can see a lot of room for improvements… just gotta rip the band-aid off and make intelligent decisions rather than just slapping an rsync job that connects to the Nextcloud instance and replicates down the files and backend database. Not terrible, but not great.

In the backend I’m already using ZFS for my files and Redis database, but my core SQL database was located on the server’s root partition (which is XFS - I’d rather not mess with a DKMS module from a boot CD if something happens and upstream borks the compile, which is precisely what happened when I upgraded to OpenZFS 2.1.15).

I do not have automatic ZFS snapshots configured at this time, but based on the above, I’m reasonably confident that I could get data back from a ZFS snapshot if any of the normal guardrails within Nextcloud failed or did not work as intended (trash bin and internal version history). Plus, the data in that cursed rsync backup should be at least 90% functional.