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  • systemd management using systemctl and journalctl to check systemd logs

    systemd is like the service manager for your Centos and other modern Linux distributions (including Debian/Mint/Ubuntu) allows you to enable services, stop them, restart them, check their status and even reboot your system. The key commands or arguments you will use with systemctl are the following: Unit Commands:   list-units [PATTERN...]         List loaded units &nbs........
  • wget how to resume download!

    It's very simple you just use the "-c" switch and wget will resume the file (make sure you are in the same directory) or specify -O /path/to/partialdownload.zip wget -c http://someurl/file.zip........
  • WD 20EARX Dead Again

    Another new drive bad from the start:   Jun  2 15:14:18 one-desktop kernel: [15895.386779] ata2.00: exception Emask 0x50 SAct 0x1 SErr 0x280900 action 0x6 frozen Jun  2 15:14:18 one-desktop kernel: [15895.386782] ata2.00: irq_stat 0x08000000, interface fatal error Jun  2 15:14:18 one-desktop kernel: [15895.386784] ata2: SError: { UnrecovData HostInt 10B8B BadCRC } Jun  2 15:14:18 one-desktop kernel: [15895.386788] ata2.00: cmd 60/0........
  • WD 20EARX 2TB Bad within days

    This is just trying to read 5GB off the drive with dd and the drive initially tested ok but shortly after I wondered why I was seeing 2MB/s read speeds.  Notice the "current_pending_sector", anytime I've seen it at anything above 0 even with no other bad fields/attributes, it means the drive is bad. ata1.00: exception Emask 0x0 SAct 0x3 SErr 0x0 action 0x0 ata1.00: irq_stat 0x40000008 ata1.00: failed command: READ FPDMA QUEUED ata1.00: cmd 60/00:00:........
  • Bad Hard Drive Slows Down Computer

    Here's a proven example of what a bad hard drive can do, it was technically functioning OK in a RAID array but the system became extremely low and the load become high and IOWAIT was even higher and I always thought it was a bad application.  The truth is that this failing 1TB Hitachi has slowly gotten worse and caused huge slowdowns, (eg. 100% load on Thunderbird waiting for e-mails to load etc..).  After swapping it out, tabs change instantly, emails are not lagged, and........
  • wget download all files on page/directory automatically recursively

    Have you ever found a website/page that has several or perhaps dozens, hundreds or thousands of files that you need downloaded but don't have the time to manually do it? wget's recursive function called with -r does that, but also with some quirks to be warned about. If you're doing it from a standard web based directory structure, you will notice there is still a link to .. and wget will follow that. Eg. let's say you have files in http://serverip/documen........
  • Linux Out of Memory OOM Object Killer Solution "Out of memory: kill process 1955 (sshd) score 81 or a child"

    I had a system running a 128MB live CD image with 2.8 gigs of available RAM and the OOM kernel killer went crazy when using dd for more than 8 minutes and kept killing everything.  I've read that this is due to a low-memory issue and paging in the kernel and 32-bit systems with lots of RAM. I even enabled swapspace on my LiveCD and the issue happened 25 minutes into dd rather than 8 minutes, so what gives? Also no swap space was ever used! cat /proc/s........
  • How To Test If Your Hard Drive Is Good/Signs of dying hard drive

    I like dd, although it only reads it, usually a read test of the entire disk will uncover if your hard drive is bad in some parts.  This is a good thing to do at least once a month, a lot of times bizarre program behavior, laginess and crashing/unnmounting problems etc.. are due to a failing disc and SMART won't know it or indicate a problem: We must also remember there's never a guarantee, I've found that ever since we moved to larger and more platters per drive with 1TB drives........
  • smart is not smart, it thinks a dead drive is still good

    I had a dying drive that smart thought until it totally disappeared was a good drive, and actually all parameters did look fine but this system was causing my system to lockup and other bad behavior:   === START OF INFORMATION SECTION === Device Model:     WDC WD20EARS-00MVWB0 Serial Number:    WD-WMAZ20139 Firmware Version: 50.0AB50 User Capacity:    2,000,398,934,016 bytes Device........
  • Hitachi 2TB HDS5C3020ALA632 drive DOA

    I had one of these shipped and it was not recognized when plugged in, here's what a dead drive looks like (I assume it's teh circuit board which is dead):   ata1: link is slow to respond, please be patient (ready=0) ata1: softreset failed (device not ready) ata1: SATA link up 3.0 Gbps (SStatus 123 SControl 300) ata1: link online but device misclassified, retrying ata1: link is slow to respond, please be patient (ready=0) ata1: softreset f........
  • Centos 5.5 RAID 1 boot issue

    I installed 5.5 with a 300GB RAID 1 partition (boot is also on this partition).  It booted up fine the first few times until after I used a Live CD and accessed the array, and it became named /dev/md127 for some reason. Now whenI boot into CentOS I get a kernel panic and different errors, once I got "invalid superblock", even though the array is fine (it didn't happen again, probably because I was sure to dismount and stop the mdadm array properly). Here's what........
  • Seagate Drive 500GB Drive Dying

    This drive is clearly on the way out, the Kernel knows it but I'm surprised that SMART is not concerned.  I didn't blame Seagate for their past issues until now.  This hard drive has hardly been used and has not even been powered on for a year according to SMART. Home page is http://smartmontools.sourceforge.net/ === START OF INFORMATION SECTION === Model Family:     Seagate Barracuda 7200.11 Device........
  • Seagate 7200.11 firmware defect in 500GB, 1000GB (1TB) and 1500GB (1.5TB) Hard Drives

    Seagate Inventory/Firmware Check I heard about this issue a long time ago but never looked into it.  I figured I wasn't affected since my 500GB drives were running for so long.  I've been using Seagate's since 2002 and to this day all of the drives I have are alive from Seagate. *Update the bad news is that I realize one of my 500GB's is about to die, it's not even a year old, but is also not affected by the recall according to Seagate! Seagate Inventory/Firm........
  • OpenVZ backup container to a single file while it's running using "vzdump"

    Proxmox has made this free utility to backup running OpenVZ containers.  It's a great program which is actually just a PERL script but gets the job done.  This program is not 100% required because all it really does is cp -a from your container's path as far as I know but it is still good to have uniformity to how you backup your containers. For RPM distros such as Centos/RHEL/Fedora etc.. download and install this: wget http://www.proxmox.com/cms_proxm........
  • resume: could not stat the resume device file

    resume: could not stat the resume device file I got that after migrating to a different physical hard drive, it wanted to resume from a swap partition that no longer exists. This is actually controlled by "uswsusp.conf" in /etc Just edit it and remove the device or change it to the correct new swap file.........
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