I am trying to set up a Raspberry Pi for 24/7 Mode.I am Using Raspbian with a GUI. In this context, I want to swap the Directory /var/log into the RAM.
I tried to ad the following entry to fstab to reach
my Requirement:
none /var/log tmpfs size=10M,noatime 00
How can i ensure, that the directory was added to the RAM?
Did i forgot something ro reach my purpose?
Do you guys have any ideas how i can swap a directory to RAM?
Thank you for your help.
You can do that with the usefull log2ram tool (https://github.com/azlux/log2ram).
It will allow you to mount the /var/log folder into RAM and archive your logs in the folder /var/hdd.log once a day or whenever you want by modifying cron script. This feature is very useful for reading your logs after a stop of your RPI!
Related
I have an instance of OpenNebula with 2 nodes running KVM and local file store. This means no live migration as vm images are scp'd to each node, so there is also no option of failover or Live Migration.
I would like to implement NFS shared storage and move the VM's from the local FS datastore to the NFS shared storage datastore. OpenNebula supports migrating VM's between datastores, but only datastores of the same type i.e. 'ssh' to 'ssh' but not 'ssh' to 'shared'.
I am working on a method of achieving this, and would love some feedback as to why this is a good or a bad idea.
Thanks
OpenNebula doesn't currently support migrating VM's from one type of datastore to another different type of datastore. I have been working on a method that is working and want to document it here to get some feedback and opinions on the method.
A datastore type is identified primarily by the Transfer manager Driver 'TM_MAD' setting. This setting cannot be changed, either through Sunstone or through the cli. So we need a method to do just this. This is what i did. I started with a fresh install of OpenNebula 5.4.13 in one VM, and 2 VM nodes all running Debian 9 within VMware virtual machines (don't forget to check virtualisation for the VM CPU options).
NOTE: This is an experimental process so make sure you Backup everything first!
Steps
To migrate to a different store, there are a few steps we need to do. They are as follows:
Setup the NFS share exports,
Move the VM images to the NFS share and mount the datastore,
Change the datastore types,
Configure the nodes for NFS share.
Setup NFS Server
First thing we want to do is setup the NFS shares that we want to use. I'm using a single share for the base datastore folder, but you could use separate shares for each datastore ID from different NFS servers.
On the NFS Server create the datastore folder i.e. mkdir /share/one_datastore,
Add the datastore path to exports and export the new share exportfs -rav,
Confirm the share is available showmount -e localhost
Prepare to Migrate
Before we modify the datastores there are a few things to do first:
Shut down any running VM's and undeploy them. This saves the machines states and copies the images back to the image store,
Stop Sunstone and OpenNebula services systemctl stop opennebula && systemctl stop opennebula-sunstone.
Migrate Data
Shared storage shares the VM disk images so all the nodes can access the same data. So copy the VM data to the NFS share ready for mounting.
From the Sunstone frontend server confirm the NFS shares showmount -e [nfs-server],
Create a temp folder to mount the share in mkdir /mnt/datastore,
Temporarily mount the NFS folder mount [nfs-server]:/share/one_datastore /mnt/datastore,
Move the datastore folders to the share mv /var/lib/one/datastores/* /mnt/datastore/
OpenNebula datastore folders now live on the NFS server: ls /mnt/datastore should list folders 0, 1 and 2,
Mount the NFS share to replace the OpenNebula datastore folder mount [nfs-server]:/share/one_datastore /var/lib/one/datastores,
Confirm the folders are available ls /var/lib/one/datastores should list our 3 folders 0, 1 and 2,
Add the mount into /etc/fstab to persist the mount on boot.
OpenNebula frontend is now configured to access the datastore folders from the NFS share. Next we want to change the datastores type from ssh to shared.
Change Datastore Types
The data for the datastore configuration is stored in the OpenNebula database /var/lib/one/one.db. We can change the driver type by editing the datastore configuration data which then tells OpenNebula whiche drivers to use, and how to handle the datastore data. By default OpenNebula uses an sqlite database with the option of MySql. i'm using sqlite but the same works for MySql.
Open the OpenNebula database sqlite3 /var/lib/one/one.db,
View all tables with .tables. datastore_pool is the table we want to modify,
List all the records in the table select * from datastore_pool; will result in a screen-full of configuration data. Each record has an identifier oid which matches the datastore ID, like this (the first 0 is the datastore ID for the default SYSTEM database):
0|system|<DATASTORE><ID>0</ID><UID>0</UID><GID>0</GID><UNAME>oneadmin</UNAME><GNAME>oneadmin</GNAME><NAME>system</NAME><PERMISSIONS><OWNER_U>1</OWNER_U><OWNER_M>1</OWNER_M><OWNER_A>0</OWNER_A><GROUP_U>1</GROUP_U><GROUP_M>0</GROUP_M><GROUP_A>0</GROUP_A><OTHER_U>0</OTHER_U><OTHER_M>0</OTHER_M><OTHER_A>0</OTHER_A></PERMISSIONS><DS_MAD><![CDATA[-]]></DS_MAD><TM_MAD><![CDATA[ssh]]></TM_MAD><BASE_PATH><![CDATA[/var/lib/one//datastores/0]]></BASE_PATH><TYPE>1</TYPE><DISK_TYPE>0</DISK_TYPE><STATE>0</STATE><CLUSTERS><ID>0</ID></CLUSTERS><TOTAL_MB>0</TOTAL_MB><FREE_MB>0</FREE_MB><USED_MB>0</USED_MB><IMAGES></IMAGES><TEMPLATE><ALLOW_ORPHANS><![CDATA[NO]]></ALLOW_ORPHANS><DISK_TYPE><![CDATA[FILE]]></DISK_TYPE><DS_MIGRATE><![CDATA[YES]]></DS_MIGRATE><RESTRICTED_DIRS><![CDATA[/]]></RESTRICTED_DIRS><SAFE_DIRS><![CDATA[/var/tmp]]></SAFE_DIRS><SHARED><![CDATA[NO]]></SHARED><TM_MAD><![CDATA[ssh]]></TM_MAD><TYPE><![CDATA[SYSTEM_DS]]></TYPE></TEMPLATE></DATASTORE>|0|0|1|1|0
Now to change the datastore type. Grab the data from the 3rd column body
(You can run select body from datastore_pool where oid=0;) and copy to your favourite text editor (that's the chunk starting with <DATASTORE> and ending with </DATASTORE>). Find and replace:
Find: <TM_MAD><![CDATA[ssh]]></TM_MAD>
Replace with: <TM_MAD><![CDATA[shared]]></TM_MAD>
Find: <SHARED><![CDATA[NO]]></SHARED>
Replace with: <SHARED><![CDATA[YES]]></SHARED>
Now to update the SYSTEM datastore record. Run the following command on the database, replacing [datastore-config] with the text block you just modified update datastore_pool set body='[datastore-config]' where oid=0,
Update IMAGE datastore is a little different. There is no SHARED option, but we want to use either shared or qcow2 drivers. I used qcow2. So: select body from datastore_pool where oid=1;:
Find: <TM_MAD><![CDATA[ssh]]></TM_MAD>
Replace: <TM_MAD><![CDATA[qcow2]]></TM_MAD>
Update the record: update datastore_pool set body='[datastore-config]' where oid=1;,
Update the FILES datastore (oid=3) by replacing <TM_MAD><![CDATA[ssh]]></TM_MAD> with <TM_MAD><![CDATA[shared]]></TM_MAD> and update using the method above.
Now that the datastores have been updated to use the shared driver, lets start Sunstone and check that the datastores show up.
systemctl start opennebula && systemctl start opennebula-sunstone
Jump into Sunstone web and go to datastores. Opening each datastore to check whether SHARED is enabled, and the correct drivers show i.e. shared or qcow2.
~DONT DO ANYTHING YET~ Still need to configure the nodes!
Configure the Nodes
So because we stopped and undeployed the VMs, there shouldn't be any data in the node datastores. So we can just set up NFS shares to the datastores folder. Confirm the folders are empty first and make sure to take backups! This is an experimental process so be warned! Right, lets get onto it:
Check the contents of /var/lib/one/datastores. If you are mounting each datastore ID based folder to its own NFS share then you can do this instead of the entire datastore folder. Empty any folders with 0, 1 and 2 folders. otherwise remove all folders from the datastores folder,
If not already installed: apt-get install nfs-common,
Check for NFS shares: showmount -e [nfs-server],
Mount the nfs share to the datastore folder: mount [nfs-server]:/share/one_datastore /var/lib/one/datastores,
Confirm the mount i.e. df,
Edit /etc/fstab adding the mount so its mounted on next boot.
Restart your node to confirm the datastore nfs persists, and to give them a restart!
Repeat with all host nodes.
Test it Out
In Sunstone go to the Hosts TAB and check they are up and running. Next go and grab a VM and deploy it. It should deploy without any issues and start booting.
Once up and running i like to constantly ping the VM while testing live migration. So start ping (ping [vm-ip] -t in windows) and then in Sunstone open the VM and do a 'Live Migrate' to another node. Watch the ping and check the logs to make sure it succeeded. I found i had to refresh the display, and go to the hosts TAB to check the VM had migrated. After that it showed correctly but i think its a caching issue in my browser. After the Live Migration you should still see the ping rolling along, with maybe one failed ping in the results.
Conclusion
So that's the process i used to migrate from ssh local storage to shared storage. I'v tested it and it is working without any issues. However, if you do have any issues or have an opinion on this process please let me know. If there are any pitfalls with this i have overlooked please also let me know.
Ok, have fun with it. I'm off to try moving the shared storage over to some kind of shared cluster like Ceph or GlusterFS!
I am trying to mount an nfs share to a solaris 10 machine at bootup without any luck so far.
The nfs share is accessible and mounts without any problems if I do so manually from the command line (mount -F nfs server_hostname:/exported_dir_path/ /mnt/tmpdir). But I don't know how to tell autofs to mount it at bootup.
We have another machine on the same network (also solaris) that has it working, but I can't figure out how is it configured differently from the non-working one.
I googled the problem and found that /etc/vfstab, /etc/auto_master, and /etc/hosts files need to have proper entries to make this work. I compared these files from the non-working machine with the ones on working machine but did not notice any differences.
Could someone please guide me to properly configure autofs to mount nfs shares on a solaris10 machine?
Thanks,
Aashish.
I have a Jenkins server running on OpenShift Origin 1.1
The pod is using persistent storage using NFS. We have a pv of 3GB and a pvc on this volume. It's bound and Jenkins is using it. But when we perform:
sudo du -sh /folder we see our folder is 15GB. So we want to resize our persistent volume while it's still in use. How can we perform this?
EDIT: or is the best way to recreate the pv and pvc on the same folder as before. So all the data will remain in that folder?
This will be a manual process and is entirely dependent on the storage provider and the filesystem with which the volume is formatted.
Suppose you have NFS that has enough space say 15 Gb and you have pv only of 3Gb then you can simply edit the pv to increase the size.
"oc edit pv [name]" works and you can edit the size of the volume.
I am new to Virtual Machines and CLI so please bear with me.
I have a CentOS 6.5 running on Compute Engine.
I ran yum update (without creating a snapshot of the previous disk - Yes I am an idiot) and not I cannot connect to the machine using the ip address.
I tried the following steps.
Tried to connect through Filezilla - didn't work.
Tried through Putty - didn't work
Tried through the browser option given by the CE console - didn't work.
I even tried creating a snapshot and starting up another VM with the snapshot - didn't work.
If anyone knows how I can get the files and folders out from the previous disk, I can start up a new VM and transfer everything again.
I do not have the latest database and this is important.
Please help!
Thanks
Warren
The way to recover is to delete your VM without deleting the disk, then create another VM with its own boot disk, attach and mount the original disk, and recover any data that you need from it.
First things first: on the VM instances page, click on the instance name that is currently running with that disk, and uncheck the box "Delete boot disk when instance is deleted". Then delete the instance.
Now, create a new instance with its own boot disk. To differentiate this new disk from the original boot disk:
using a different OS (or version of the OS) for the new disk, e.g., if using Ubuntu, try a different version or use Debian; if using RHEL, try CentOS, or vice versa
see which one is mounted at / — this should be the new disk
Mount the original disk as read-only and recover any information you need. Once you have a backup of your data, you can remount it with read-write access and try to fix it (but back up the data first!).
I finally solved this problem thanks to Misha for sending me in the right direction.
The steps are below for anyone who has the same issue.
Problem:
While updating the Centos server using yum update, I was unable to connect back to the server.
I tried all possible combinations but no luck. This seems to be a known issue as there was some material on the Compute Engine site regarding this.
Solution:
I followed the steps as Misha suggested. I started up another VM with its own boot disk and then attached the original disk with read write access.
Note: I was unable to mount the disk as just read only.
The commands were
mkdir /mnt/sdb1
mount /dev/sdb1 /mnt/sdb1
Once I mounted the VM, I copied the files from the html folder in the sdb1 disk to the html folder in the sda1(the new boot disk).
The database was a bit more challenging.
I tried quite a few times but copying the files from /dev/sdb1/var/lib/mysql into the new disk mysql folder was not working.
I found some tutorials but nothing helped.
Finally I downloaded the files from within the /dev/sdb1/var/lib/mysql and put them in my local windows mysql installation within the data folder.
Remember you have to download everything which includes the ib_logfile0 , ib_logfile1 and ibdata1 including the folder which has the *.frm files.
Then I opened localhost/phpmyadmin and voila... the files were there.
The rest was pretty simple... Exporting and uploading the SQL scripts back to the server.
This took me about 12 hours to figure out.
Thanks again Misha.
I have several web applications in production that utilize NFS mounts to share resources (usually static asset files) among web heads. In the event that an NFS mount becomes unavailable, Apache will hang requesting files that cannot be accessed, the kernel will log:
Nov 2 14:21:20 server2 kernel: nfs: server server1 not responding, still trying
I reproduced the behavior in RHEL5 running NFS v3 and Apache 2.2.3:
Create an NFS Mount on Server1 (contents of my /etc/exports)
/srv/test_share server2(rw)
Mount the NFS share on Server2 (contents of my /etc/fstab)
server1:/srv/test_share /mnt/test_share nfs defaults 0 0
Setup a virtual host in Apache with a simple HTML file referencing image files stored on the NFS sharen
Load the site, the html and image files all return 200
Unmount the NFS Share, loading the page returns 404s for the images referenced
Remount the NFS Share
Simulate an NFS crash by turning NFS off on Server1 - reloading the site hangs retrieving the referenced files.
Internet searches so far have not turned up a good solution. Basically the desired behavior would be for the web server to return 404s and not hang until the NFS mount recovers.
Cheers,
Ben
couple of options:
get your nfs mount options right, you need to do a soft mount so nfs access can be interupted. try soft,intr,timeo=10 instead of default
sync your document roots with something else like rsync, or script yourself a semi-atomatic checkout/export from your SCM, if you use one. SCM use is recommended anyway, gives you the possibility to revert to the last working version, for instance
use a real distributed filesystem (preferably fault tolerant like coda) or even a distributed block device system like drdb
option 2 and 3 give you disconnected operation and are therefore much more robust than nfs. drdb is sexy, but my advice would be option 2 with somwething like git or svn, simple and robust
I would not directly serve from the NFS mount, but instead from your local filesystem.
It wouldn't be too hard to setup a cron job that synced the NFS mount to the local file system every few minutes. Apache would serve its content from there, not depending on the NFS mount. If the mount goes down, Apache would still be able to serve the assets, although they might be out of date until the NFS mount comes back up.