The Smell of Molten Projects in the Morning

Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.

Category: PC Tweakage

Remembering which tweaks worked

  • Lenovo Q150 Restoration Utility

    The general idea was to put the old Lenovo Q150 to work as a dedicated Superformula generator attached to the HP 7475A plotter: connect the serial cable, fire ’em up, and It Just Works. As part of the first pass, I installed Mint Linux atop an old Ubuntu install, got Python & Chiplotle set up, and That Just Works:

    Lenovo Q150 with HP 7475A
    Lenovo Q150 with HP 7475A

    However, the Q150 sports a dual-core Intel Atom, underpowered even back in the day, that hasn’t gotten any peppier over the years. The Lenovo-installed Windows 7 pushed the CPU hard enough to require full-throttle fan whine, even at idle, and mysterious issues with memory usage (something involving a memory leak in svchost.exe or perhaps over-aggressive Windows Update prefetching) reduced performance to a crawl as the system paged its brains out to the 5400 RPM laptop-style drive (*). As part of this adventure, I figured I’d boot the Lenovo restore partition and burn Win 7 back to bedrock before installing Mint.

    Turns out that the Lenovo restore utility doesn’t work when the drive has an unusual partition structure; it tells you to repartition the drive and try again. So I blew away the Ubuntu installation’s extended partition (containing swap, main, and spare partitions), then rebooted, only to discover that, of course, the missing partitions contain Grub’s later stages. Having previously wasted far too much time trying to resuscitate various half-dead Grubs, I created a fourth partition, installed Mint Linux (ignoring its strenuous objections about not having a swap partition) to refresh Grub, booted the Lenovo restore utility, and ended up at a raw Windows terminal emulator box atop a picture of some weird tropical greenery. Apparently the restore utility depends on something that got blown away during all the flailing around.

    So, just for completeness, I shrank Mint a bit, added a swap partition, and got the results shown above. One core runs at 100%, probably dribbling bytes to the USB-to-serial adapter, but the thing runs much cooler. In this context, it should be noted, a 110 °F surface and 140 °F exhaust temperature counts as “cool”; the fan isn’t at full throttle, but it’s surprisingly noisy for a computer billed as a multimedia streaming device.

    I actually have a complete backup of the original contents of all three partitions, so I could whack it back to mid-2011. Modulo, of course, resetting the actual partition sizes and positions and suchlike, which I’m sure will be vital to having the restore utility do its thing. Maybe that’s worthwhile just to remind me why it’s such a terrible idea.

    (*) Blowing $50 on an SSD is so not happening, OK?

     

  • Fixing the Sudo Timeout

    So I can find it again, the way to change the sudo timeout for a particular user (that would be me) involves adding a line to the /etc/sudoers file using sudo visudo, thusly:

    Defaults:       ed timestamp_timeout=90
# blank line to make the underscore visible

    Note the colon! Should you add the timeout to the global Defaults env_reset line, then everybody gets a monster timeout, which may not be what you want.

    You can change the default editor (nano in Ubuntu) thusly:

    sudo update-alternatives --config editor

    Or, in Arch / Manjaro, add a stanza:

    Defaults	editor=/usr/bin/nano

    Because my vi hand is weak:

    • :wq to save & exit
    • :q! to bail out
    • i and a at cursor, I and A in line
    • o and O at line
    • ␛ back to command mode

    That’s all I need to insert the proper stanza & move on.

  • Time Warner RoadRunner vs. SSH: Help Wanted

    So Time Warner updated the infrastructure upstream of Mary’s folks and installed a new cable modem / router, which killed my remote access using ssh (with RSA keys, passphrases, nonstandard ports, fixed internal IP addresses, port forwarding, port triggers, and all the Right Stuff). I just spent a harried pair of days trying and failing to figure out how to make this work again.

    My laptop can ssh into my file server from our house network, both wired and wireless. Ditto when it’s on the Squidwrench Operating Table. Ditto from the low-quality Hampton Inn WiFi near her folks. Plunked on their desk and jacked into their router, however, that outbound ssh times out somewhere between their bits and my basement.

    I dinked with the TW Surfboard modem / router, added the appropriate port forwarding & triggers, dialed back the firewall intensity, and ssh flat out doesn’t work in either direction from any PC (all running various Linus flavors). No diagnostics, no logs, nothing that I could find.

    From the outside (our house or the Hampton), there’s no response from the PCs inside (on their desk). I’m not trying a loopback from inside to inside, which I know doesn’t work with consumer-grade routers. I’d planned to ssh from there to my basement file server, then ssh back to verify that the connections worked, but the outbound connection doesn’t work.

    Probably unrelated, but equally frustrating: trying to configure Thunderbird’s outbound SMTP with their email server flat-out doesn’t work. Either the username / password isn’t valid (it is), various combination of ports / security / encryption (including the ones in the TW FAQs) don’t survive the configuration test, or a seemingly valid configuration doesn’t actually transmit email. Incoming email works only in IMAP mode, not POP3.

    I finally set up outbound TW email to bankshot through his Gmail account, which will probably have unforeseen side effects.

    The usual Google searches were unavailing, other than several notes suggesting that if you have any other choice of ISP or email provider than TW, do that. But it’s not like they have any choice; Verizon provides 1 Mb/s (!) DSL in that area and satellite Internet isn’t going to happen in an apartment.

    Obviously, I’m doing several things wrong, but I have no idea what else to try. I’ve set up email and remote access often enough to get a whole bunch of things right, but that sure didn’t help with TW.

    Any suggestions?

  • Why Friends Don’t Let Friends Run Windows

    Perhaps this is not nearly as motivational as it’s supposed to be:

    Win 10 Upgrade Popup
    Win 10 Upgrade Popup

    A friend sent that along after reading my efforts to squelch the Windows 10 nagware on an off-lease Dell Optiplex that will never, ever be updated.

    She just turned off automatic updates, which means she must examine all the updates and manually install ones that don’t download Win 10 (which she doesn’t want), forevermore. Unfortunately, that means she won’t automatically get all the security updates that help make current versions of Windows much less hazardous then in The Bad Old Days.

    Talk about a Hobson’s Choice: in practical terms, you must decide between automatic updates or not getting regular updates. OK, that’s actually a false dilemma, but you get the idea.

    If you run automatic updates the way Microsoft recommends, you’ll soon be running a free operating system that tracks and reports your every move, so as to deliver precisely targeted advertisements right on your desktop. What could possibly be better?

    Come the middle of next year, we may see an uptick in the number of people using Linux or running unpatched Windows boxes to cut down on nagware.

  • Disabling Windows 10 Upgrade Nagware

    If you’re running Windows, then you have more experience than I do, but it seems Microsoft, for reasons best known to it, really really really wants you to upgrade to Windows 10, has been forcing nagware onto every Windows box in existence, and actively working to defeat efforts to remove said nagware.

    Our Token Windows Box, an off-lease Dell Optiplex 780 that arrived bearing Windows 7 Professional, will never, ever get upgraded, because it’s running a bunch of ancient Windows programs that interface with specific bits of hardware, none of which (most likely) will work with Windows 10. In any event, I see no reason to go through the hassle of “upgrading” an old machine, (maybe) resolving all the inevitable compatibility problems, and (maybe) having no way to roll back the upgrade, all for a few programs run, at most, monthly.

    Continually declining Windows 10 upgrade prompts isn’t my idea of a Good User Experience, but I’m also tired of manually inspecting and killing updates that re-re-re-install the nagware.

    The GWX Control Panel (“GWX” = “Get Windows 10” in MS-speak) seems to be the least awful way of dealing with this mess. It’s not offered by Microsoft, for obvious reasons, but is offered free-of-charge.

    Just do it…

  • USB-to-SATA Drive Adapter Performance

    The discussion about scrubbing hard drives suggested I really should be using larger block sizes to wring better performance from the hardware.

    So I ran variations on this theme:

    time sudo dd if=/dev/urandom of=/dev/sdc bs=4K count=32K

    For the BS (“block size”) parameter, 1K = 1024 and 1KB = 1000. Similarly for 1M vs. 1MB.

    The results, viewed as a picture because WordPress seems unable to import a formatted spreadsheet from LibreOffice like it used to:

    USB-SATA Adapter - Barracuda 7200.10 drive
    USB-SATA Adapter – Barracuda 7200.10 drive

    Each operation transfers 128 MB (128 x 220 = 131 x 106) bytes. The variations probably come from other stuff going on, most notably the USB-to-serial adapter driving the plotter while I’m testing a tweak to the Superformula demo code.

    Reads ever so much faster than writes, so the USB adapter definitely isn’t getting in the way; I assume the drive accepts the commands & data as fast as its little heads can carry them away. The data, being relentlessly pseudo-random, won’t get compressed along the way.

    So, in round numbers, the block size just absolutely does not make any difference.

    Update: Based on an early comment from Edward Berner to a previous post, I was looking in the wrong place:

    dd if=/dev/urandom of=/dev/zero bs=4K count=32K
32768+0 records in
32768+0 records out
134217728 bytes (134 MB) copied, 9.63064 s, 13.9 MB/s
dd if=/dev/urandom of=test.bin bs=4K count=32K
32768+0 records in
32768+0 records out
134217728 bytes (134 MB) copied, 10.018 s, 13.4 MB/s
dd if=test.bin of=/dev/zero bs=4K count=32K
32768+0 records in
32768+0 records out
134217728 bytes (134 MB) copied, 0.0385358 s, 3.5 GB/s
dd if=test.bin of=test2.bin bs=4K count=32K
32768+0 records in
32768+0 records out
134217728 bytes (134 MB) copied, 0.45044 s, 298 MB/s

    I installed an SSD on this box a while ago, so the 3.5 GB/s disk-to-discard speed represents the SSD’s read rate. The 298 MB/s disk-to-disk speed would be its write speed, probably with some clever buffering going on.

    So the real bandwidth limitation in wiping a disk comes from the pseudo-random generator behind /dev/urandom, not the disk or USB interface. It would probably be faster to fill a 1 GB (or more) file with noise at 14 MB/s, then copy it enough times to fill the drive at whatever speed the drive can handle it.

    Thanks, Edward, for figuring that out!

  • SATA vs. USB Hard Drive Write Speeds

    The stack of drives-to-be-scrubbed disgorged a pair of SATA drives, so I plugged one of them into an internal SATA port and unleashed dd on it:

    time sudo dd if=/dev/urandom of=/dev/sdb bs=4096 count=10000
10000+0 records in
10000+0 records out
40960000 bytes (41 MB) copied, 4.19793 s, 9.8 MB/s

real	0m4.208s
user	0m0.004s
sys	0m2.880s

time sudo dd if=/dev/urandom of=/dev/sdb bs=1024 count=40000
40000+0 records in
40000+0 records out
40960000 bytes (41 MB) copied, 7.38392 s, 5.5 MB/s

real	0m7.394s
user	0m0.004s
sys	0m3.505s

time sudo dd if=/dev/urandom of=/dev/sdb bs=16384 count=2500
2500+0 records in
2500+0 records out
40960000 bytes (41 MB) copied, 4.2042 s, 9.7 MB/s

real	0m4.214s
user	0m0.000s
sys	0m2.880s

    The timing for a few (tens of) thousand blocks comes out somewhat below the long-term average, which was the same 12 to 14 MB/s produced by the USB 2.0 adapter. It just doesn’t get any better than that, mostly due to rotational delays.

    In round numbers, that’s 40 to 50 GB/h, so it’s best to start scrubbing those terabyte drives early in the day…