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> USB/Pendrive Slowness
John Cuppi
 Posted: Apr 21 2013, 06:32 PM
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I installed SL6.4 to my 4gb flash drive using liveusb-creator with a persistent filesystem of around 2gb. Everything works fine except for one major problem - I get lag spikes for no reason when the system isn't even doing anything.

Observing iotop which I installed, it appears to be a problem with the persistent filesystem:

http://i1.someimage.com/viN0fjs.png

I can let this sit and it will happen pretty often with little to nothing going on. I'm posting this message from this installation and haven't had any freeze ups but it occurs so much that it makes everything slow from trying to browse around to installing packages, really anything.

What can I do? This flash drive isn't crappy and I've tested it recently. I have also had various Ubuntu, Backtrack, and a couple others installed that I didn't like and those didn't give me this problem with a persistent filesystem.

Any suggestions would be welcome here.

Thanks!
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tux99
 Posted: Apr 21 2013, 07:09 PM
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Hmm, just guessing here as I have never tried this, but maybe it's because of the specific filesystem you used? Or maybe it's incorrect block alignment?

Can you post a fdisk -l of the usb stick and the output of mount?

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John Cuppi
 Posted: Apr 21 2013, 11:22 PM
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Sure, here it is, any ideas welcome.

CODE
[root@livecd liveuser]# fdisk -l

Disk /dev/sda: 64.0 GB, 64023257088 bytes
255 heads, 63 sectors/track, 7783 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x000d9764

  Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1          13      102400    7  HPFS/NTFS
Partition 1 does not end on cylinder boundary.
/dev/sda2              13        7784    62417920    7  HPFS/NTFS

Disk /dev/sdb: 4051 MB, 4051697664 bytes
128 heads, 42 sectors/track, 1472 cylinders
Units = cylinders of 5376 * 512 = 2752512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0xc3072e18

  Device Boot      Start         End      Blocks   Id  System
/dev/sdb1   *           1        1472     3956704+   b  W95 FAT32

Disk /dev/mapper/live-rw: 4294 MB, 4294967296 bytes
255 heads, 63 sectors/track, 522 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000


Disk /dev/mapper/live-osimg-min: 4294 MB, 4294967296 bytes
255 heads, 63 sectors/track, 522 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


And mount:

CODE
[root@livecd liveuser]# mount
/dev/mapper/live-rw on / type ext4 (rw,noatime)
proc on /proc type proc (rw)
sysfs on /sys type sysfs (rw)
devpts on /dev/pts type devpts (rw,gid=5,mode=620)
tmpfs on /dev/shm type tmpfs (rw,rootcontext="system_u:object_r:tmpfs_t:s0")
none on /proc/sys/fs/binfmt_misc type binfmt_misc (rw)
/dev/sdb1 on /mnt/live type vfat (rw)
varcacheyum on /var/cache/yum type tmpfs (rw,mode=0755,rootcontext="system_u:object_r:rpm_var_cache_t:s0")
/tmp on /tmp type tmpfs (rw,rootcontext="system_u:object_r:tmp_t:s0")
vartmp on /var/tmp type tmpfs (rw,rootcontext="system_u:object_r:tmp_t:s0")
sunrpc on /var/lib/nfs/rpc_pipefs type rpc_pipefs (rw)
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tux99
 Posted: Apr 21 2013, 11:56 PM
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Like I said I haven't tried this myself so I'm not quite sure what's wrong here, but I would have formatted the USB stick with ext2 first rather than leaving it FAT32, it could be the fact that it's FAT32.

Also I usually repartition USB sticks from scratch using fdisk -S 32 -H 32 /dev/sdX (where X is the appropriate device letter) before using them for optimum alignment.

That said I have no idea if these two suggestions would make a difference in your case or if there is a different problem.

--------------------
My personal SL6 repository, specialized in audio/video software: http://pkgrepo.linuxtech.net/el6/
(can be used together with EPEL and ELRepo repositories) - repository mirror: http://linuxsoft.cern.ch/linuxtech/el6/
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John Cuppi
 Posted: Apr 22 2013, 02:31 AM
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You might be right.

The reason it's fat 32 is simply because I did this via windows and didn't think it would be a problem since I haven't had this experience before with the other distros leaving it fat32.

I'll give it a shot when I have the time and report back. It's certainly worth a try.

Thanks.
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John Cuppi
 Posted: Apr 25 2013, 08:17 AM
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Okay, so I reformatted the pendrive using ext2 but I'm still plagued with the same problem. I guess it's not FAT32.

I think I will try throwing fedora on here and see if it's just liveusb-creator.
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tux99
 Posted: Apr 25 2013, 04:44 PM
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Another thought: were you using a USB 3.0 port? If yes then try a USB 2.0 port instead.

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(can be used together with EPEL and ELRepo repositories) - repository mirror: http://linuxsoft.cern.ch/linuxtech/el6/
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John Cuppi
 Posted: Apr 25 2013, 05:26 PM
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No USB 3.0 ports on any of my machines.

I tried different ports as well to see if one had gone bad... and nothing.
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John Cuppi
 Posted: Jun 10 2013, 10:40 PM
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Okay so it's been a while and I became extremely busy after I'd posted that, but I had some time to give this all a test once again and to no avail. Ext2 showed no improvement again but it was worth a shot. I tried the system on two completely different computers, one being my netbook and the other being my desktop. Both showed the same issue with iotop and the loop having a high iowait.

I decided to throw fedora 18 on this pen drive which I'm posting from right now on my desktop and there are no issues at all. i/o top only shows a little bit of i/o being used now and then while browsing around and that's to be expected. There aren't these 99% spikes.

I only have USB 2.0 ports on all of these machines but really from all of my testing here it appears something isn't right with SL6.4 and maybe earlier versions with a persistent filesystem. I've had a few other live images on this drive with persistent filesystems as I mentioned earlier and I gave Ubuntu a shot again as well before trying Fedora and it's worked perfectly.

I guess I'm just going to accept that I'm not going to be able to get this to work. It's not a big deal to me though because I just wanted to have linux available on my pen drive all the time for the heck of it, and wanted it to be SL but that's not going to work out for me sadly. I don't have another USB drive with me to test to see if it's just something up with this drive right now, but I'm out of possible ideas here otherwise.
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tux99
 Posted: Jun 10 2013, 10:48 PM
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I'd suggest post your findings on the SL-devel mailing list and maybe also on the Centos mailing list, there you might get more qualified feedback from the developers.

--------------------
My personal SL6 repository, specialized in audio/video software: http://pkgrepo.linuxtech.net/el6/
(can be used together with EPEL and ELRepo repositories) - repository mirror: http://linuxsoft.cern.ch/linuxtech/el6/
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