[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [gcmd-usr] A rather strange g-c experience

From: kht-lists
Subject: Re: [gcmd-usr] A rather strange g-c experience
Date: Tue, 08 Jan 2019 15:41:39 +0000

Thanks Michael,

The motherboard is only a couple of years old and has USB 3 ports. It is the 
flash drive which is USB 2. Sandisk Cruiser Blade - $4.99 US from Walmart - one 
of their back to school special purchases.  Four years ago they had a 4 GB for 
$4.99, the next year 16 GB and for the past two years 32 GB. Slow but cheap. 
Ideal for this particular purpose.

I am familiar with the caching and USB drives. Copying starts FAST - until 
caching by the OS is filled and then sloooow. If I "eject" the drive 
immediately after the copy finishes it does take a while until the drive 
signals ready to remove.

As to an addon adapter... I have a USB 2 card in the machine to run an OLD 
Brother multi-function printer/scanner/fax device. I spent 3 weeks working with 
a fellow in New Zealand on linuxquestions.org on that one. I could print when 
it was connected to a USB 3 port but not scan. In fact I could not scan if it 
was connected to a USB 2 port in a machine with USB 3 available on other ports. 
It has been working fine after I added a "Hi speed" USB 2 board - $3.95 
delivered from evilbay :-)


p.s. Did you ever get my .deb file to install g-c on your machine?

Sent with ProtonMail Secure Email.

‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
On Tuesday, January 8, 2019 10:10 AM, Michael <address@hidden> wrote:

> Hi Ken,
> I've never had a comparable issue with g-c, but more often such issues with 
> USB in general.
> From your report i conclude that you are probably copying with USB 2.0 speed 
> (and not even fully) so i assume your motherboard ist old. Mine is too, and 
> the USB ports even are flakey meanwhile. So, it happens that an inserted USB 
> drive 'dies'.
> Any kind of stuff related to drive I/O can zombie a Linux OS. Just some 15 
> minutes ago i issued accidently an hdparm sleep command to a SATA drive which 
> was already in sleep mode, and the process immediately went zombie (could not 
> be killed even with -9) and prevented even a regular shutdown.
> I think Linux I/O drivers have serious weaknesses here.
> You should alse take into account that flash drives have internal cache. If 
> you trnasmit huge amount of data, the file manager will signal 'done' but the 
> drive is still busy with writing, for some more 2-3 minutes. If the flash 
> controller has to TRIIM the already written storage blocks (which happens all 
> the way along the normal operations) then it might be even like 5 minutes, 
> worst case. I can see this with my old USB 2.0 stuff all the time. (You need 
> a drive with LED to be able to recognize its activity clearly). If you remove 
> the drive before the internal cache and trim operations are finished, the 
> file system immediately is broken and probably data is lost, even if fsck can 
> fix it.
> Once a fat32 drive is not cleanly unmounted (for whatever reason) the dirty 
> bit is set, and it refuses to mount again. Run fsck (or dosfsck) to evaluate.
> So, my best guess is that g-c was either requesting some disk info (maybe 
> just the directory) which terminal or caja don't, but the drive was not ready.
> Or else, the muonting itself was not working (fast enough?) for g-c, which 
> might be a bug; but then worked for terminal because the g-c try already 
> changed things. It would be tedious to reproduce with your complex setup, it 
> should be done with a simple test environment. But honestly, since USB (and 
> especially 2.0) already is flakey kernel-wise, i would not want to do it; 
> there are definitely more serious problems in the pipeline.
> As a rule of thumb, g-c is not the ideal tool to access problem drives or for 
> copying huge amounts of data, since it gots too less feedback. You should 
> always test new drives from a terminal, always run a initial fsck, and if 
> it's about huge amounts of data, i recommend midnight commander (a terminal 
> app) who has nice indicators, and it's own copy modes (like, contents of 
> dcirectories one after the other, as opposed to 'cp' which copies based on 
> file size.)
> As for the slow USB (if my guess was right) - it really pays off to copy on a 
> fast USB 3 machine. If you don't have one, consider bying an PCI Express <-> 
> USB adaptor card, which will let you copy USB with PCIE speed. (But if your 
> USB drive, or even just the cable to an USB harddrive, itself is only 2.0 
> specified, you will only yield max USB 2 speed.)
> > Naturally the journal feature of ext4 took up just enough space that the 
> > files would not fit.
> There is exfat which solves many fat32 problems (especially file size and 
> naming limits) while still uses maximal space. With Linux desktops, you need 
> to install the drivers manually, depending on the OS (yes with Debian), and 
> have to mount with sudo.
> You may save some EXT4 space with the marked 'XXX' mk2efs options:
> -L ......... Label
> -n ......... simulate
> -c -c ...... slow r/w bad blocks test (Needs awful lot of time!)
> -t ext4 .... Filesystem type
> -j ......... create Journal
> -m 0 ....... 0% superuser XXX
> -O Options: large_file,dir_index, sparse_super XXX
> Note: extent,resize_inode are default for ext4

reply via email to

[Prev in Thread] Current Thread [Next in Thread]