FAQ for unRAID v6

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This thread is reserved for Frequently Asked Questions, concerning unRAID as a NAS, its setup, operation, management, and troubleshooting.  Please do not ask for support here, such requests and anything off-topic will be deleted or moved, probably to the FAQ feedback topic.  If you wish to comment on the current FAQ posts, or have suggestions or requests for the FAQ, please put them in the FAQ feedback topic.  Thank you!


Index to common questions

  Some are from the wiki FAQ, some from this thread, and some from the LimeTech web site.  There are many more questions with answers on the wiki FAQ.

Getting Started

General Questions

Cache Drive/Pool


Maintenance and Troubleshooting




unRAID FAQ's and Guides -

* Guides and Videos - comprehensive collection of all unRAID guides (please let us know if you find one that's missing)

* FAQ for unRAID v6 on the forums, general NAS questions, not for Dockers or VM's

* FAQ for unRAID v6 on the unRAID wiki - it has a tremendous amount of information, questions and answers about unRAID.  It's being updated for v6, but much is still only for v4 and v5.

* Docker FAQ - concerning all things Docker, their setup, operation, management, and troubleshooting

* FAQ for binhex Docker containers - some of the questions and answers are of general interest, not just for binhex containers

* VM FAQ - a FAQ for VM's and all virtualization issues


Know of a question that ought to be here?  Please suggest it in the FAQ feedback topic.



Suggested format for FAQ entries - clearly shape the issue as a question or as a statement of the problem to solve, then fully answer it below, including any appropriate links to related info or videos.  Optionally, set the subject heading to be appropriate, perhaps the question itself.


While a moderator could cut and paste a FAQ entry here, only another moderator could edit it.  It's best therefore if only knowledgeable and experienced users create the FAQ posts, so they can be the ones to edit it later, as needed.  Later, the author may want to add new info to the post, or add links to new and helpful info.  And the post may need to be modified if a new unRAID release changes the behavior being discussed.


Moderators:  please feel free to edit this post.

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Why am I unable to install plugins?


With some user's network setup (ISP, router, etc) you may need to manually set static DNS addresses so that unRaid can communicate with the outside world.


Go to Settings, Network Settings and enter in the appropriate addresses (You can always use Google's DNS server addresses which are and


In some cases, this may be caused by misconfiguration of your network bonding settings.  You can try deleting /config/network.cfg on the flash drive (to restore default settings), then reboot unRaid and try again

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What counts as a drive against my license storage device limit?


Everything that is handled by Linux as a storage device (basically everything except for your boot flash drive).  This includes DVD / Bluray drives, card readers, external hard drives and the like.


If you exceed your device limit (whether assigned to the array or not), you will either have to remove those devices from your service, or upgrade your license.


Note that the Pro versions of unRAID have no device limits and only limit the amount of devices able to be actually assigned to the array.

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Why is my cache disk(s) unassigned after a reboot?


Some users have this issue when using Chrome to add cache disk(s), single cache disk or one or more disks from a cache pool don't stay assigned after a reboot, use IE or Firefox for this operation, use it for the complete procedure, assign cache disk(s), start array, stop array and reboot, your assignments should stick now.


If using a different browser doesn't work, boot unRAID in safe mode, assign your cache devices, start array, stop array and reboot in normal mode, assignments should now stick.



Edited by johnnie.black
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Can I manually create and use multiple btrfs pools?


Multiple cache pools are supported since v6.9, but for some use cases this can still be useful, you can also use multiple btrfs pools with the help of the Unassigned Devices plugin.


There are some limitations and most operations creating and maintaining the pool will need to be made using the command line, so if you're not comfortable with that wait for LT to add the feature.


If you want to use the now, here's how:


-If you don't have yet install the Unassigned Devices plugin.

-Better to start with clean/wiped devices, so wipe them or delete any existing partitions.

-Using UD format the 1st device using btrfs, choose the mount point name and optionally activate auto mount and share

-Using UD mount the 1st device, for this example it will be mounted at /mnt/disks/yourpoolpath

-Using UD format the 2nd device using btrfs, no need to change the mount point name, and leave auto mount and share disable.

-Now on the console/SSH add the device to the pool by typing:

btrfs dev add -f /dev/sdX1 /mnt/disks/yourpoolpath

     Replace X with correct identifier, note the 1 in the end to specify the partition (for NVMe devices add p1, e.g. /dev/nvme0n1p1)


-Device will be added and you will see the extra space on the 1st disk free space graph, whole pool will be accessible in the original mount point, in this example:


-By default the disk is added in single profile mode, i.e., it will extend the existing volume, you can change that to other profiles, like raid0, raid1, etc, e.g., to change to raid1 type:

btrfs balance start -dconvert=raid1 -mconvert=raid1 /mnt/disks/yourpoolpath

     See here for the other available modes.


-If you want to add more devices to that pool just repeat the process above




-Only mount the first device with UD, all other members will mount together despite nothing being shown on UD's GUI, same to unmount, just unmount the 1st device to unmount the pool.

-It appears that if you mount the pool using the 1st device used/free space are correctly reported by UD, unlike if you mount using e.g. the 2nd device, still for some configurations the space might be incorrectly reported, you can always check it using the command line:

btrfs fi usage /mnt/disks/yourpoolpath

-You can have as many unassigned pools as you want, example how it looks on UD:




sdb+sdc+sdd+sde are part of a raid5 pool, sdf+sdg are part of raid1 pool, sdh+sdi+sdn+sdo+sdp are another raid5 pool, note that UD sorts the devices by identifier (sdX), so if sdp was part of the first pool it would still appear last, UD doesn't reorder the devices based on if they are part of a specific pool.


You can also see some of the limitations, i.e., no temperature is shown for the secondary pools members, though you can see temps for all devices on the dashboard page, still it allows to easily use multiple pools until LT adds multiple cache pools to Unraid.


Remove a device:

-to remove a device from a pool type (assuming there's enough free space):

btrfs dev del /dev/sdX1 /mnt/disks/yourpoolpath 

     Replace X with correct identifier, note the 1 in the end


Note that you can't go below the used profile minimum number of devices, i.e., you can't remove a device from a 2 device raid1 pool, you can convert it to single profile first and then remove the device, to convert to single use:

btrfs balance start -f -dconvert=single -mconvert=single /mnt/disks/yourpoolpath

Then remove the device normally like above.


Replace a device:

To replace a device from a pool (if you have enough ports to have both old and new devices connected simultaneously):


You need to partition the new device, to do that format it using the UD plugin, you can use any filesystem, then type:

btrfs replace start -f /dev/sdX1 /dev/sdY1 /mnt/disks/yourpoolpath


Replace X with source, Y with target, note the 1 in the end of both, you can check replacement progress with:

btrfs replace status /mnt/disks/yourpoolpath


If the new device is larger you need to resize it to use all available capacity, you can do that with:

btrfs fi resize X:max /mnt/disks/yourpoolpath

Replace X with the correct devid, you can find that with:

btrfs fi show /mnt/disks/yourpoolpath



Screenshot 2018-03-18 14.42.51.png

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Why is the webGUI not displaying any of my shares, but I can see them over the network?


Some of the commercial / free adblockers for Windows / (Mac?) are incorrectly flagging your unRaid server's GUI as an advertisement.  In your adblocker's settings, there should be an option to "white-list" your server.

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What is the Local Master in SMB and does it involve the Internet?



I answered a query recently and complied a response which is referenced here:


The next post suggested that the information be added to the WIKI.  I could see it going into the Networking section (#10) but I am unsure the way to do this.  Do you want to be the one controlling this since you are revising the entire FAQ?  I would be happy to rework this post and make it a bit more general if that would help. 

Edited by Frank1940
updated link
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  • 2 weeks later...
  • 2 months later...

How do I add a disk to create a redundant cache pool?


A few notes:

-unRAID v6.4.1 or above required, upgrade first if still on an older release.

-Current cache disk filesystem must be BTRFS, you can’t create a pool from an XFS or ReiserFS cache.

-Always a good idea to backup anything important on the current cache in case something unexpected happens

-When first creating a pool with 2 or more devices initial profile used will be raid1, this can be changed later.

-When a device is added to an existing pool the profile in is use is maintained, i.e., you have two disk raid0 pool and add a third device it will be a three device raid0 pool in the end.




  • stop the array
  • change cache slots to 2 or the correct number
  • assign new disk(s) to cache pool
  • start array - a balance will begin, the stop array button will be inhibited during the operation, this can take some time depending on how much data is on the pool and how fast your devices are, progress can also be seen on WebGUI cache page “btrfs balance status”
  • when balance is done or the stop array button is available the replacement is done, "btrfs balance status" should show "No balance found on '/mnt/cache'", check also that "btrfs filesystem show" total devices are correct.



Edited by johnnie.black
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How do I remove a cache pool disk?


A few notes:

-unRAID v6.4.1 or above required, upgrade first if still on an older release.

-Always a good idea to backup anything important on the current cache in case something unexpected happens

-You can only remove devices from redundant pools (raid1, raid5/6, raid10, etc) but make sure to only remove one device at a time, i.e., you can't remove 2 devices at the same time from any kind of pool, you can remove them one at a time after waiting for each balance to finish (as long as there's enough free space on the remaining devices).

-You can't remove devices past the minimum number required for the profile in use, e.g., 3 devices for raid1c3/raid5, 4 devices for raid6/raid10, etc, exception is removing a device from a two device raid1 pool, in this case Unraid converts the pool to single profile.

-Some Unraid releases like current stable v6.8.3 permit removing devices from non redundant pools, but this is not officially supported, the pool itself can't be encrypted and the device being removed must remain connected while the pool is balanced to the new profile, there might be other gotchas so proceed with care.





  • stop the array
  • unassign pool disk to remove
  • it's OK to reorder remaining pool members if you want (but see point below), i.e., you had a three device pool and removed cache2, you can assign cache3 to slot2 before starting the array (you can also do it later)
  • while it's OK to reorder members it's currently not OK to change the number of cache slots at the same time you remove a device, you can do that after the pool is balance down, i.e., just don't do both things at the same time.
  • start the array (after checking the "I'm sure" box next to the start array button)
  • a balance and/or a device delete will begin depending on the profile used and number of pool members remaining, wait for cache activity to stop, the stop array button will be inhibited during the operation, this can take some time depending on how much data is on the pool and how fast your devices are.
  • when the cache activity stops or the stop array button is available the replacement is done.



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How do I replace/upgrade a cache pool disk?


NOTE: currently broken on v6.9.x (fixed on v6.10-rc3 and later)


A few notes:

-unRAID v6.4.1 or above required, upgrade first if still on an older release.

-Always a good idea to backup anything important on the current cache in case something unexpected happens

-This procedure assumes you have enough ports to have both the old and new devices connected at the same time, if not you can use this procedure instead.

-Current cache disk filesystem must be BTRFS, you can’t directly replace/upgrade an XFS or ReiserFS disk.

-On a multi device pool you can only replace/upgrade one device at a time.

-You can directly replace/upgrade a single btrfs cache device but the cache needs to be defined as a pool, you can still have a single-device "pool" if the number of defined cache slots >= 2 Currently not working.


-You can't directly replace an existing device with a smaller one, only one of the same or larger size, you can add one or more smaller devices to a pool and after it's done balancing stop the array and remove the larger device(s) (one at a time if more than one), obviously only possible if data still fits on the resulting smaller pool.





  • stop the array
  • on the main page click on the cache device you want to replace/upgrade and select the new one from the drop down list (any data on the new device will be deleted)
  • start the array
  • a btrfs device replace will begin, wait for cache activity to stop, the stop array button will be inhibited during the operation, this can take some time depending on how much data is on the pool and how fast your devices are.
  • when the cache activity stops or the stop array button is available the replacement is done.
  • if the new device is larger than the one being replaced you need to stop/re-start the array once the replacement is done for the new capacity to be available.





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I have two different size cache devices, why is the reported space incorrect?


Old Unraid bug when using different size devices (fixed on v6.9-beta30), usable size in default 2 device pool RADI1 config is always equal to the smallest device.


Although free pool space is incorrectly reported the cache floor setting should still work normally (at least for unRAID v6.2 and above), i.e., set it according to the real usable space.


To see the usable space with 3 or more different size devices in any profile use the calculator below:




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Can I change my pool to RAID0 or other modes?


Yes, for now it can only be manually changed, new config will stick after a reboot, but note that changing the pool using the WebGUI, e.g., adding a device, will return cache pool to default RAID1 mode (note: starting with unRAID v6.3.3 cache pool profile in use will be maintained when a new device is added using the WebGUI, except when another device is added to a single device cache, in that case it will create a raid1 pool), you can add, replace or remove a device and maintain the profile in use following the appropriate procedure on the FAQ (remove only if it does not go below the minimum number of devices required for that specific profile).


It's normal to get a "Cache pool BTRFS too many profiles" warning during the conversion, just acknowledge it.


These are the available modes (enter these commands on the cache page balance window e click balance**, note if the command doesn't work type it instead of using copy/past from the forum, sometimes extra characters are pasted and the balance won't work)


** Since v6.8.3 you can chose the profile you want from the drop-down window and it's not possible to type a custom command:




All the command below can still be used on the console:


Single: requires 1 device only, it's also the only way of using all space from different size devices, btrfs's way of doing a JBOD spanned volume, no performance gains vs single disk or RAID1

 btrfs balance start -dconvert=single -mconvert=raid1 /mnt/cache


RAID0: requires 2 device, best performance, no redundancy, if used with different size devices only 2 x capacity of smallest device will be available, even if reported space is larger.

btrfs balance start -dconvert=raid0 -mconvert=raid1 /mnt/cache
RAID1: default, requires at least 2 devices, to use full capacity of a 2 device pool they all need to be the same size.


btrfs balance start -dconvert=raid1 -mconvert=raid1 /mnt/cache


RAID10: requires at least 4 devices, to use full capacity of a 4 device pool they all need to be the same size.

btrfs balance start -dconvert=raid10 -mconvert=raid10 /mnt/cache


RAID5/6 still has some issues and should be used with care, though most serious issues have been fixed on current kernel at this of this edit 4.14.x


RAID5: requires at least 3 devices.

btrfs balance start -dconvert=raid5 -mconvert=raid1 /mnt/cache


RAID6: requires at least 4 devices.

btrfs balance start -dconvert=raid6 -mconvert=raid1 /mnt/cache
Note about raid6**: because metadata is raid1 it can only handle 1 missing device, but it can still help with a URE on a second disk during a replace, since metadata uses a very small portion of the drive, you can use raid5/6 for metadata but it's currently not recommended because of the write hole issue, it can for example blowup the entire filesystem after an unclean shutdown.
** Starting with Unraid v6.9-beta1 btrfs includes support for raid1 with 3 and 4 copies, raid1c3 and raidc4, so you can use raid1c3 for metadata to have the same redundancy as raid6 for data (but note that the pool won't mount if you downgrade to an earlier release before converting back to a supported profile on the older kernel):
btrfs balance start -dconvert=raid6 -mconvert=raid1c3 /mnt/cache




-d refers to the data, -m to the metadata, metadata should be left redundant, i.e., you can have a RAID0 pool with RAID1 metadata, metadata takes up very little space and the added protection can be valuable.


When changing pool mode confirm that when the balance is done data is all in the new selected mode, check "btrfs filesystem df"on the cache page, this is how a RAID10 pool should look like:


Data, RAID10: total=14.00GiB, used=9.85GiB

System, RAID10: total=224.00MiB, used=16.00KiB

Metadata, RAID10: total=2.19GiB, used=10.23MiB

GlobalReserve, single: total=16.00MiB, used=0.00B


If there is more than one data mode displayed, do the balance again with the mode you want, for some unRAID releases and the included btrfs-tools, eg, v6.1 and v6.2 it's normal needing to run the balance twice.

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  • 1 month later...

What is "Boot GUI mode", and how do I change to it?


Some users run unRAID as headless, and if you do, then this FAQ is not for you.  The Boot GUI is a GUI replacement for the text based terminal screen on the server console that we have always seen after boot, until now.  It provides the same unRAID screens on the server monitor that you normally get when you open your unRAID server from a browser on another desktop.


One important requirement - a mouse!  If you have never viewed a GUI on your server machine, then you may not have one attached, and any GUI requires a mouse.  Because support is built in, getting a mouse working should be easy, but may not be (and you may have to reboot).


To set the GUI mode, go to the Main screen and click on your unRAID flash disk (on the word 'Flash'), to open its settings page.  Go down to the Syslinux Configuration section.  This is a viewer and editor of your syslinux.cfg file, the file that controls the boot menu for your server.  After some preliminary general settings lines, you will see a series of sections that begin with label.  Each section controls a separate menu line on your boot menu.  In one of them is the line "menu default", which marks the menu item that will be performed if nothing is selected within the allotted time.


To change the default menu selection, simply move the "menu default" line into the section you want to be the default, then click Apply then Done.  Try it and see, you can always change it back.


One warning!  This uses Firefox as the browser to open the unRAID server management pages.  It's fine for that, but because it's a browser, it will be tempting to go on the Internet.  It is NOT configured to securely access the Internet!  Don't do it!  To be safe, use it only for managing your unRAID server.  (This author is not sure of the security implications and dangers here, and prefers to err on the side of safety.)


An example of a modified syslinux.cfg -

default /syslinux/menu.c32
menu title Lime Technology, Inc.
prompt 0
timeout 50
label unRAID OS
  kernel /bzimage
  append initrd=/bzroot vga=6
label unRAID OS GUI Mode
  menu default
  kernel /bzimage
  append initrd=/bzroot,/bzroot-gui vga=6
label unRAID OS Safe Mode (no plugins, no GUI)
  kernel /bzimage
  append initrd=/bzroot unraidsafemode vga=6
label Memtest86+
  kernel /memtest

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  • 2 weeks later...

I have a new SAS drive.  How do I get unRAID to recognize and assign it?

Why can't unRAID find or add my SAS drive?


Assuming you are running unRAID 6.2, go to Settings -> Display Settings and change Display world-wide-name in device ID from Disabled to Automatic.  Click Apply then Done, and then go see if unRAID will let it be assigned!

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  • 1 month later...

I set a share to private, created a user set read/write permissions to that share.  But on my windows 7 PC when i try to navigate to that share it's saying I don't have access when i put the user name and password. Did I miss anything?


Here is a explanation of what is happening from LimeTech:


Edited by Frank1940
updated linnk
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I'm getting an error message " Failed to find user 'avahi' ".  What do I do?

Why after upgrading to a 6.2 version is my webGUI so slow?

Why is my webGUI taking so long between pages?



- the error message "Failed to find user 'avahi'", usually in the syslog but may appear on the console too

- changing pages in the webGUI will take from 20 to 40 seconds per page

- some combination of the following sequence of lines appears over and over in the syslog:

Aug  5 13:52:02 DarkTower emhttp: shcmd (20782): /etc/rc.d/rc.avahidaemon start |& logger

Aug  5 13:52:02 DarkTower root: Starting Avahi mDNS/DNS-SD Daemon:  /usr/sbin/avahi-daemon -D

Aug  5 13:52:02 DarkTower avahi-daemon[20325]: Failed to find user 'avahi'.

Aug  5 13:52:22 DarkTower root: Timeout reached while wating for return value

Aug  5 13:52:22 DarkTower root: Could not receive return value from daemon process.

Aug  5 13:52:22 DarkTower emhttp: shcmd (20783): /etc/rc.d/rc.avahidnsconfd start |& logger

Aug  5 13:52:22 DarkTower root: Starting Avahi mDNS/DNS-SD DNS Server Configuration Daemon:  /usr/sbin/avahi-dnsconfd -D

Aug  5 13:52:22 DarkTower avahi-dnsconfd[20428]: connect(): No such file or directory

Aug  5 13:52:22 DarkTower avahi-dnsconfd[20428]: Failed to connect to the daemon. This probably means that you

Aug  5 13:52:22 DarkTower avahi-dnsconfd[20428]: didn't start avahi-daemon before avahi-dnsconfd.


For as yet unknown reasons, the internal 'avahi' user is missing from some users unRAID systems, and this avahi user has become more important for the proper functioning of the avahi daemons in 6.2 and later.  This missing user results in long timeouts while the avahi daemons try over and over to re-initialize.


The solution is to edit the passwd file on your boot flash disk ( /boot/config/passwd ), and add the following 2 lines to it:

avahi:x:61:214:Avahi Daemon User:/dev/null:/bin/false
avahi-autoipd:x:62:62:Avahi AutoIP Daemon User:/dev/null:/bin/false 

Then edit the shadow file on your boot flash disk ( /boot/config/shadow ), and add the following 2 lines to it:  (this may be needed for proper security)



You will need to use a Linux-aware editor to preserve correct Linux style line endings.  You can use the built-in mc or nano.  It's often easier to use copy and paste in Windows or Mac, just make sure you preserve the Linux style line endings.  You may have to reboot for it to take effect, or at least restart the array.  This post may be edited further as more info comes in.

Edited by RobJ
fix formatting for IPS
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How do I replace/upgrade my single cache device? (unRAID v6.2 and above only)


This procedure assumes that there are at least some dockers and/or VMs related files on the cache disk, some of these steps are unnecessary if there aren't.

  • Stop all running Dockers/VMs
  • Settings -> VM Manager: disable VMs and click apply
  • Settings -> Docker: disable Docker and click apply
  • Click on Shares and change to "Yes" all cache shares with "Use cache disk:" set to "Only" or "Prefer"
  • Check that there's enough free space on the array and invoke the mover by clicking "Move Now" on the Main page
  • When the mover finishes check that your cache is empty (any files on the cache root will not be moved as they are not part of any share)
  • Stop array, replace cache device, assign it, start array and format new cache device (if needed), check that it's using the filesystem you want
  • Click on Shares and change to "Prefer" all shares that you want moved back to cache
  • On the Main page click "Move Now"
  • When the mover finishes re-enable Docker and VMs



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  • 4 weeks later...

I have software that requires using port 80.  How do I change the HTTP port that unRAID uses?


First, be certain that's what you really want, as changing the unRAID port should normally be a last resort.  It's usually much better to change the port your app needs instead.  Docker container ports can usually be remapped.


Currently, the only way is to edit your go file, and start emhttp with a different port.  The go file is at /boot/config/go if you are editing it in a terminal, at \\tower\flash\config\go if you are editing it from Windows (change 'tower' as needed).


Find this line in the go file:

  /usr/local/sbin/emhttp &

And change it to:

  /usr/local/sbin/emhttp  -p  ##  &

Where ## is the new port number you want to use to reach your unRAID server webGUI.


Then reboot the server.


Don't forget that you will also need to change the location in your browser!


Example:  set emhttp port to 8080

  /usr/local/sbin/emhttp -p 8080 &

Reboot your unRAID server, then browse to it on the new port


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Is there a way to create a Windows shortcut for shutting down the unRAID server?


On your Windows machine:

- Install PuTTY first, it includes plink.exe

- Create a batch file (store it anywhere you choose) containing the following line (replace password_here and server_IP_here):

    plink.exe  -ssh  -pw  password_here  [email protected]server_IP_here  poweroff

    e.g. plink.exe -ssh -pw 123456 [email protected] poweroff

    Note: with older versions of unRAID, use powerdown instead of poweroff

- Create a shortcut on your Windows desktop that points to that batch file


Clicking that shortcut should start the normal unRAID shutdown procedures.

Edited by RobJ
add poweroff
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  • 3 weeks later...

I found a segfault error in my syslog.  How do I fix it?

My system is crashing randomly, and/or I'm seeing a little data corruption.  How do I fix it?

How do I test my RAM, my system memory?


* Segfaults - there are 2 primary reasons for segfaults - faulty memory chips and dependency issues.  See below for methods to test your RAM.  If your RAM is fine, then it's almost certainly a dependency issue - some software that you have added has a dependency that conflicts with either the core unRAID system or something else you have added.


* Random crashes and data corruption - while there could be a number of causes for both of these, one primary cause and the easiest to test and fix is faulty RAM.  Thoroughly test your memory using one or both of the following methods.


The 3 symptoms above are the most common symptoms of bad RAM chips, but there are others too such as kernel OOPS and kernel panics and other syslog errors resulting in a 'Call Trace'.  While there may be other causes for these, the first test you should always do (and the easiest!) is to thoroughly test your memory chips.  The following 2 methods will test your RAM for problems, and report any errors found.  IMPORTANT!  Not one error is acceptable!  If you run a Memtest for 12 hours and it only finds one problem, then you need to replace a RAM stick!  You absolutely HAVE to be able to trust your memory.  When you test memory, you expect 100% perfection, no matter how long you test!


Note: there are 2 different Memtest programs, Memtest86 and Memtest86+.  They look very much alike for good reason - they have the same base code!  When the original development stopped in 2002, for about 2 years, an open source group created Memtest86+ from the code, and continued updating it until stopping in 2013, with v5.01 being their last release.  The free open source Memtest86+ v5.01 is what is included with unRAID.  PassMark Software bought the rights to the original code in 2013, and has been updating it ever since, as MemTest86, currently at v7.2.  Many newer technologies and tests have been added, such as DDR4, extensive ECC testing, row hammer testing, and much more.  The newer features do require UEFI support, and if not found, an older version will be booted instead.  While it's now a commercial product, they have continued offering a free version, for personal use only, but it is not licensed for inclusion with the unRAID software distribution.


Note 2: both methods assume you can view what is on the console of the unRAID server.  That usually means an attached monitor and keyboard, but could also mean remote viewing through IPMI.  There is NO WAY to run a memory test on a headless server (unless you can use IPMI).  To run either method, you MUST find a way to view the console, and you need a keyboard to select the test.  The PassMark Memtest can also use a mouse, so an attached mouse will be very helpful in Method 2.


* Method 1 - using the built-in Memtest

  • You MUST be able to see the console and use a keyboard to select Memtest from the boot menu.
  • On booting your unRAID server, when the boot menu appears, select Memtest, and it will begin.  It will run continuously until you reboot.

* Method 2 - using the PassMark Memtest

  • You MUST be able to see the console and use a keyboard to select Memtest(?).  A mouse will also be very helpful, recommended.
  • (download from PassMark, create bootable USB drive, configure UEFI settings to boot UEFI, boot, after completion restore UEFI settings)
  • PassMark download
  • PassMark installation help
  • (work in progress)


Bad memory defects will fail the tests on the very first Memtest pass.  Once you see the first error, you can stop the test as there's no point in continuing.  Unfortunately, other memory defects are much harder to find, marginal cells that appear to work fine *most* of the time.  *Most* of the time is not good enough, they need to be perfect *all* of the time.  So you will need to let the tests run a long time, waiting for that marginal cell to fail.  Again, even one error means a bad memory stick.  How long is long enough?  I believe over night, or 12 hours is sufficient, but it's possible that in some circumstances, even longer may be needed.


If you do get an error, then you will want to isolate which stick is bad and which ones are fine.  That means alternately testing different combinations of sticks, or each stick individually.


This is a work in progress, but almost ready to put online!

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