My darn NAS...

CG> > Even if I won't get the 100mb/s that I had THOUGHT, I'd probably see a b CG> > transfer rate anyway. Hmmmmm... CG> Is it really that important or significant? I.e. does it really CG> matter if a transfer takes 15 seconds rather than 10 seconds? CG> CG> I run my (incremental, so rarely really huge) backups overnight via CG> anacron so whether they take 10 minutes or 30 minutes doesn't matter CG> at all. As long as they complete before I wake up in the morning it's CG> fine.

While I suppose you're right about the bigger backups being at night, the files I work with WOULD benefit from any and all transfer increases. I mean... a lot of 4k movies & videos, backups of 1TB drives, etc etc.

Yes, nighttime backups can go so far.. but I do sit and wait while things transfer. A lot.

I still haven't went to the network room and put the laptop on the ethernet - I'm going to... maybe today.

I'm thinking that if, while connected to ethernet, I get good transfer rates that way I'll just connect to ethernet if I'm going to do a bunch of big transfers - and I might check into getting the latest Wifi chips across my entire network so that when on Wifi its at least a LITTLE quicker. If I can do both of those things I think I'll be pretty well setup.

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paul lee
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TN> I now have an Ethernet cable to where the laptop lives

I have a feeling that, in the end, this is gonna be the ticket.

|07p|15AULIE|1142|07o |08.........

Reply to
paul lee

Is it really that important or significant? I.e. does it really matter if a transfer takes 15 seconds rather than 10 seconds?

I run my (incremental, so rarely really huge) backups overnight via anacron so whether they take 10 minutes or 30 minutes doesn't matter at all. As long as they complete before I wake up in the morning it's fine.

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Chris Green
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Chris Green

That does not gybe with what is reported on my gear. Top raw speed even rammed up against the router is 72Mbps.

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Reply to
The Natural Philosopher

in general I have found that on a good link, speeds of a little over

1/10th Mbps rate to be obtained at the byte level, So overheads is not that heavy a penalty.

Probably ~10% That's on a *full duplex* link. Broadband is full duplex. Ethernet of the cat 5 sort is full duplex.

Wifi is NOT full duplex.

That means that any ACK packets going back share bandwidth with the forward data stream, In a fairly nasty 'wait till the stream packet size is exceeded, then send an ack oh dear collisions/backoffs/try again...' sort of way.

When my Pi zero link was going titsup before I slapped in an access point 5 feet away, although it *said* it was connected at 5Mbps, it couldn't support a 128kbps stream of audio. My so called 72Mbps links couldn't handle HD TV, which is around 5Mbps I think, reliably.

I now have an Ethernet cable to where the laptop lives

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Reply to
The Natural Philosopher

It starts to matter when live streams - audio or video - start to fail and stutter...

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The Natural Philosopher

Your mission, should you choose to accept it, is to devise a better approach that allows full duplex wifi. As always, should you or any of your IM Force be caught or killed, the Secretary will disavow any knowledge of your actions. This post will self-destruct in five seconds.

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Reply to
Ahem A Rivet's Shot

Yes, that's exactly what I was trying to say really, on a wired connection one gets something over the 1/10 the Mbp/s in MBp/s.

Simply having to interleave the ACKs with the data going in the other direction will slow things down considerably.

I use WiFi for as little as I possibly can. About the only major use is using my laptop interactively like now, replying to usenet posts and such.

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Chris Green
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Chris Green

Shannon tells you its a hiding to nothing. If you use say two frequency bands, you would get better performance just adding them together and using collision detection.

The radio spectrum is limited and precious. Go up to light frequencies and there's lots more speed available. But that doesn't punch through solid walls..

The best bet is to put a wifi point in every room, and feed them all via cable, and manage them so that StupidDevices? are only allowed to log on to the nearest one

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The Natural Philosopher

Depends on the codecs involved. If you're slinging around MPEG-2 streams that were broadcast OTA, they could take up to 20 Mbps, though 8-12 for the primary stream is closer to typical.

Years ago, I wanted to connect a MythTV backend over WiFi. 802.11g wouldn't cut it. There theoretically should've been enough bandwidth, but I think there was too much other nearby crap on the 2.4-GHz band that interfered. I was able to get decently reliable streaming of recorded TV when I switched to 802.11a, as hardly anybody else (and nobody nearby) was using 5 GHz at the time.

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Scott Alfter

Re: Re: My darn NAS... By: The Natural Philosopher to Chris Green on Thu Jan 14 2021 11:06 am

I agree with this position.

I know that just backing up the data that is not easily reproductible suffices, in theory. However, if you only back the data up without the applications and the OS stack, your recovery consits on a sysadmin installing software for a week and swearing at his notebook.

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Richard Falken

Ah we have the solution - modulated X-Rays.

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Steve O'Hara-Smith                          |   Directable Mirror Arrays 
C:\>WIN                                     | A better way to focus the sun 
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Reply to
Ahem A Rivet's Shot

well you may well laugh...why stop there. Gamma rays?

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The Natural Philosopher

Re: Re: My darn NAS... By: TimS to All on Thu Jan 14 2021 11:43 am

Hard link based incremental backups are great. I do a lot of it with rsync. There is something worth mentioning, though:

You may use hard link based backups in order to make a snapshot per week, but if a file remains unchanged for long, all your hard links will be pointing to the same file in your backup drive. This means if the file gets corrupted you have no copies of it despite having 500+ "images". I have seen it happen and it is not pretty.

It didn't happen to me, thankfully :-P BUt it pays to run some integrity checks fro tieme to time, or at least have backups of the backup.

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Richard Falken

When you backup a 1TB drive do you actually copy the whole 1TB? It's a huge waste of time and space and you can't keep so many backups. Use some form of incremental backup and also backup *selectively*.

I just backup /home, /etc and a few other odds and ends that have customisation or configuration in them. There are ready made incremental backup systems like rsnapshot which I used for a while but then I wrote my own (quite similar but does *exactly*) what I want. There's no need to back up /usr as you can simply reinstall everything there.

For example on my desktop machine I keep short-term incremental backups on a separate drive, my 1TB /home is 38% full but my multilevel incremental backups only occupy 20% of the 1TB backup drive. 'Multilevel' means I have hourly backups for the last 9 hours, daily backups for the last 7 days and weekly backups for 5 weeks.

My longer term (daily) backups go to an offsite machine, a typical incremental backup of my 38% full /home plus the other bits and pieces only takes a couple of minutes because only the *changes* since the day before are saved.

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Chris Green
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Chris Green

depends on what you want. I rsync huge amounts of data. Disk space is cheap. Recovering from data loss is not, Working out what is important and what is not is even more expensive.

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Reply to
The Natural Philosopher

Incremental backup as done by Time Machine allows many more backups. It's done with hard links, so a file is backed up the first time, but hard links are created for subsequent backups. This means that what is presented to me when I want to do a restore from a selected date just looks an ordinary folder as it would appear on the Desktop. I highlight one or more files/folders with the mouse and click Restore. No farting about with command line options that I have no interest in remembering.

Disk space may be cheap, but then you have to manage it. And remember - if you make backup/restore complicated then noddy users won't do it.

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Tim
Reply to
TimS

You can make it as easy as you like and they still won't. A long time ago I set up a system for a customer with an overnight backup schedule and prepared a box of QIC tapes labelled Mon, Tue, Wed, Thu, Fri, Fri, Fri and left instructions to change the tape daily and keep all but one of the Fri tapes offsite cycling them round each week. Many months later the hrd disc failed during the nightly backup so after replacing the drive and finding the backup corrupt I asked for the previous night's tape - it emerged that they had *never* changed the tape.

We all learned something that day.

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Reply to
Ahem A Rivet's Shot

well what I have on my SECOND drive is complete directory trees of three machines and its all exported by NFS so all I have to do is mount it , navigate to the file I need and move it across to where it needs to go.

Hardly onerous!

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The Natural Philosopher

Exactly. My rsyncs are done by 3 am cronjob. I have two VPSes out there in internet land, and one big server in house. They all get copied onto a secondary disk. If any disk goes, I have full backups, except if the secondary disk goes I have a BIG cronjob the night and day after a new one goes in :-)

I have never really successfully restored from a tape. And the drive costs more than 4TB of disk.

So far i've had one backup drive die on me - well nearly. started giving errors.

And accidentally deleted a file and restored it from last nights backup half a dozen times, and rebuilt *this* desktop completely using the backup as a source of remembering what config changes I had made to a raw install.

Works for me. YMMV

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The Natural Philosopher

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