crankbearing Posted January 8, 2012 Posted January 8, 2012 I just started a preclear on a new 3tb drive and this is a new server with 1 3tb and 3 new 2tb I installed the setup on 5b14. It is running at about 122mb/s on the 3tb right now. Is it possible to run preclear on at least one of the other drives concurrently in a new telnet window. sorry if this has been asked before. thanks, Dave
Takkie1970 Posted January 8, 2012 Posted January 8, 2012 Preclearing With Screen This is the preferred method of using the preclear script. It takes a long time! (see preclear times for different drives here). The problem without using "Screen" is when you have to telnet to your server. That connection must be uninterrupted for a full 24+ hours, or it will fail - don't pass go, do not collect $200. Using "Screen" will enable you to log into your box, start up the preclear script, then log out. Set it, and forget it. Note: Screen is not installed by default. Instructions for installing UnMENU and screen. Step 1 Open a telnet session to your UnRAID server and login as root. Or use the one you left open previously. Step 2 To navigate to the preclear script, at the prompt type cd /boot Step 3 At the prompt type screen Depending on the version of Screen installed, an information screen may show up. If you see bash: screen: command not found it indicates you did not yet download and install screen. If you see Cannot find terminfo entry for 'vt100' it indicates your telnet client's emulation is not compatible with screen. Try a different emulation type or use Putty, which works well with screen. If you invoke screen and it shows an introductory page, press Space or Return to continue and you will be returned to the prompt. Now that you are running inside a "Screen" you can create multiple prompts and even disconnect from your telnet session and processes will continue to run in the background. Note: If you are preclearing any AF drives, be sure to use the -A option when you invoke the preclear script. i.e replace ./preclear_disk.sh /dev/sdX with ./preclear_disk.sh -A /dev/sdX Step 4 To begin the preclear on the 1st drive, at the prompt type ./preclear_disk.sh /dev/sdX where sdX is the device mapping of the drive you want to preclear. If this is an IDE device it will be hdX. Note: If you have only SATA drives and see a /dev/hdX device it indicates you have set your motherboard BIOS to have it emulate an older IDE drive to the operating system. This is NOT desired for SATA drives since they will not be able to use any of their more advanced features. You instead want ACHI mode, not legacy mode. If you installed mail and ssmtp and wish to have email notifications of the process, instead of the above type ./preclear_disk.sh -M 4 /dev/sdX ("root" email address) or ./preclear_disk.sh -m [email protected] /dev/sdX (optional email address) Put your email address and sdX is the device mapping of the drive you want to preclear. If this is an IDE device it will be hdX. Note: if you do not supply either a "-a" or "-A" option, the preclear_disk.sh script will use the setting you've elected in the unRAID "settings" screen as its default partition type. -a will override the default and create an MBR-un-aligned partition starting on sector 63. -A will override the default and create an MBR-4k-aligned partition starting on sector 64. This will present you with a screen similar to Pre-Clear unRAID Disk ######################################################################## Device Model: WDC WD20EARS-00J2GB0 Serial Number: WD-WCAYYXXXXXXX Firmware Version: 80.00A80 User Capacity: 2,000,398,934,016 bytes Disk /dev/sde: 2000.3 GB, 2000398934016 bytes 255 heads, 63 sectors/track, 243201 cylinders, total 3907029168 sectors Units = sectors of 1 * 512 = 512 bytes Disk identifier: 0x00000000 Device Boot Start End Blocks Id System /dev/sde1 63 3907029167 1953514552+ 0 Empty Partition 1 does not end on cylinder boundary. ######################################################################## Are you absolutely sure you want to clear this drive? (Answer Yes to continue. Capital 'Y', lower case 'es'): Double check to make sure the Drive model and/or serial number are what you expect. If everything is copacetic type "Yes" and press enter like the box tells you too. When you do, EVERYTHING on the drive will be DELETED. The screen will clear when you respond with 'Yes' and be replaced with one showing progress and automatically updating at regular intervals. This will allow you to track the progress of the clearing of the drive. Step 5 Now that the first preclear is running, to start the next one press CTRL-A c That translates to hold down the Control key and press the A key. Release both keys then press the c key. This creates a new screen inside Screen and gives you a new prompt. Start the preclear for this drive just like the preclear for the first one. You can create a new screen for each preclear you need to run, however, it is not recommended to run more than 4 at once. Step 6 Now that the preclears are running to cycle through them and check on their status press CTRL-A n This will take you to the next screen and will loop back to the beginning when you reach the end. To go to the previous screen press CTRL-A p It will loop back to the end when you reach the beginning. You can keep your telnet session open to keep tabs on the progress and if you accidentally get disconnected the processes will remain running. You can also manually disconnect from your session by typing CTRL-A CTRL-D you will be returned to the prompt with a message that screen has detached. At this point you can terminate your telnet session. At a later time you can establish a new telnet session and reattach to Screen to check on the status of your preclears. Step 7 To reattach to the Screen, log in via telnet or on the system console as root. At the prompt type screen -r This will take you to your first screen and you can cycle through as noted above. Step 8 When your preclears have finished there will be a message on the screen that the drive either successfully passed or failed the preclear process as well as a diff of the pre and post SMART reports. There is some information in this forum post on how to interpret the results of the diff. Also if you have questions about your result the appropriate place to ask them is in this thread. See below for instructions on saving the results. Specifically look for increases of the "raw" count of re-allocated sectors and sectors pending re-allocation. Most of the other "raw" values are meaningful only to the manufacturer of the disk drive. If your diff report is long some of it may have scrolled off the screen. To see it press CTRL-A [ You will get a notice at the bottom of the screen that you are in copy mode. Now you can use the Page up and Page down keys to scroll up and down and view the results. Press Esc to exit copy mode. Step 9 As your drives finish preclearing, you can close their screens by pressing CTRL-D to logout of that screen. or you can simply type exit You will then be taken to the next or the previous screen in the buffer. When the last drive finishes and you close its screen you will get a message that screen is terminating. At this point it is recommended that you save your preclear results for future reference or so you can post them to the forum if you have any questions regarding the results. Step 10 To save your results, at the prompt type grep preclear /var/log/syslog | todos >> /boot/preclear_results.txt This will save all the relevant lines from the syslog to the preclear_results.txt file on your flash drive. You can then copy this file to another computer and peruse your results or post them to the forum. [edit]Preclearing Without Screen If you did not install screen, you can preclear your hard drives from the console. Linux provides 6 Virtual Terminals (V-Terms) that you can use from the console. It is possible to run a preclear in a telnet instance, however it is highly not recommended because if your session is interrupted, the preclear process will be terminated. If you wish to take that risk, you can substitute each Vterm with a new telnet session. Step 1 Log in to your UnRAID server as root at the console Step 2 To navigate to the preclear script, at the prompt type cd /boot Note: If you are preclearing any AF drives, be sure to use the -A option when you invoke the preclear script. i.e replace ./preclear_script.sh /dev/sdX with ./preclear_script.sh -A /dev/sdX Note: Drives greater than 2.2TB in size automatically use a GPT partition that is always aligned on a 4k boundary. The "-a" and "-A" options on the preclear script are ignored on those drives > 2.2TB as those options only apply to drives <= 2.2TB. Step 3 To begin the preclear on the 1st drive, at the prompt type ./preclear_disk.sh /dev/sdX where sdX is the device mapping of the drive you want to preclear. If this is an IDE device it will be hdX. If you installed mail and ssmtp and wish to have email notifications of the process, instead of the above type ./preclear_disk.sh -m [email protected] -M4 /dev/sdX Put your email address in and substitute for sdX the device mapping of the drive you want to preclear. If this is an IDE device it will be hdX. This will present you with a screen similar to Pre-Clear unRAID Disk ######################################################################## Device Model: WDC WD20EARS-00J2GB0 Serial Number: WD-WCAYYXXXXXXX Firmware Version: 80.00A80 User Capacity: 2,000,398,934,016 bytes Disk /dev/sde: 2000.3 GB, 2000398934016 bytes 255 heads, 63 sectors/track, 243201 cylinders, total 3907029168 sectors Units = sectors of 1 * 512 = 512 bytes Disk identifier: 0x00000000 Device Boot Start End Blocks Id System /dev/sde1 63 3907029167 1953514552+ 0 Empty Partition 1 does not end on cylinder boundary. ######################################################################## Are you absolutely sure you want to clear this drive? (Answer Yes to continue. Capital 'Y', lower case 'es'): Double check to make sure the Drive model and/or serial number are what you expect. If everything is copacetic type "Yes" and press enter like the box tells you too. When you do, EVERYTHING on the drive will be DELETED. Step 4 Now that the first preclear is running, to start the next one press ALT-F2 to go to Vterm 2. You can repeat steps 1-3 to start the preclear on the next hard drive. To get to Vterm 3 press ALT-F3 You can use this to access 6 Vterms by using F1-F6. The preclear script in each Vterm runs independently and you can keep an eye on the process of each one by switching back and forth with Alt-Fx. Step 5 When your preclears have finished there will be a message on the screen that the drive either successfully passed or failed the preclear process as well as a diff of the pre and post SMART reports. There is some information in this forum post on how to interpret the results of the diff. Also if you have questions about your result the appropriate place to ask them is in this thread. See below for instructions on saving the results. If your diff report is long some of it may have scrolled off the screen. To "scroll up" to see it you can use Shift-Page up and Shift-Page down to scroll around in the buffer. Step 6 As your drives finish preclearing, you can close their Vterms by pressing CTRL-D to logout of that Terminal or by typing exit at the linux prompt. At this point it is recommended that you save your preclear results for future reference or so you can post them to the forum if you have any questions regarding the results. Step 7 After all preclears have finished to save your results, at the prompt on Vterm 1 (Alt-F1) type grep preclear /var/log/syslog | todos >> /boot/preclear_results.txt This will save all the relevant lines from the syslog to the preclear_results.txt file on your flash drive. You can then copy this file to another computer and peruse your results or post them to the forum.
jortan Posted January 8, 2012 Posted January 8, 2012 Just to make it more clear, you can ignore all the stuff about using "screen" if you want to preclear 6 drives or less. Just hit ALT-F1 to F6 to switch between 6 terminal windows on the console of your unRAID machine. Log in as normal and preclear one drive on each terminal.
dgaschk Posted January 8, 2012 Posted January 8, 2012 Step 10 To save your results, at the prompt type grep preclear /var/log/syslog | todos >> /boot/preclear_results.txt This will save all the relevant lines from the syslog to the preclear_results.txt file on your flash drive. You can then copy this file to another computer and peruse your results or post them to the forum. This step is not needed. Reports are automatically stored in /boot/preclear_reports. Always make sure that your running the latest version of pre-clear (currently 1.13).
leg0 Posted January 9, 2012 Posted January 9, 2012 Also if you use telnet and do not want to tie up your windows machine, I believe you can use "nohup" before the preclear command. This way you can turn off your windows machine without waiting for the preclear to finish. I have not tried this personally though.
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