Advanced search

Message boards : Technical Support : how to determine resrources virtualbox/cosmo are being used

Author Message
David
Send message
Joined: 17 Apr 17
Posts: 6
Credit: 3,763,928
RAC: 16,596
Message 21348 - Posted: 28 Apr 2017, 23:04:03 UTC

1. Since boinc/cosmo are running in a virtualbox, how can I tell where everything is physically?

I ask because I have an nvme drive as boot/sda but I don't want it thrashing all the time so i want the workfiles for cosmo to reside somewhere on sdb, if the disks are hit frequently. These nvme drives are NOT cheap and will wear out so if the drive is heavily used, I want it to use the sbb, which is a mechanical SATA drive. Of course, if it is all happening in RAM (32 Gb) then the point is moot, unless the saves that happen every so often make heavy use of the main drive. So, how do I determine which is happening, and if needed, how to force the data files to reside on sdb?

Thanks.

Misho
Send message
Joined: 25 Apr 14
Posts: 9
Credit: 868,880
RAC: 0
Message 21349 - Posted: 29 Apr 2017, 3:45:12 UTC

Hello David.
I am not sure that my answer is right but i think it is.
I have 32GB ram too and have RAMdisk (4GB) where i install BOINC manager AND VirtualBox software. When i check the task of C@H in virtualbox the virtual machines are stored in this RAMdisk and i think nothing is in my HDD. But i am not sure that this is 100% right.
I hope that someone from C@H will answer better than me.

Jim1348
Send message
Joined: 17 Nov 14
Posts: 48
Credit: 2,358,299
RAC: 0
Message 21351 - Posted: 29 Apr 2017, 14:04:11 UTC - in response to Message 21348.

I would just use a write-cache, which directs all writes to the RAM memory until it is flushed to the SSD, thereby saving the SSD from most of the writes. Though if you have a crash, then you lose the unwritten data, but that is no big deal for me, since I use dedicated machines that seldom crash, and I have a backup power supply (UPS) to guard against power losses.

This is what I use on Ubuntu 16.10 for using half (16 GB) of my 32 GB main memory for a cache, and setting a two-hour time between cache flushes:

Set write cache to 16 GB: for 32GB main memory:
sudo sysctl vm.dirty_background_bytes=16000000000
sudo sysctl vm.dirty_writeback_centisecs=1000 (checks the cache every 10 seconds)
sudo sysctl vm.dirty_expire_centisecs=720000 (pages older than 2 hours are flushed)

Also, I turn off swap, since it is not normally needed with that much memory anyway:
sudo sysctl vm.swappiness=0

And it appears that Linux is smart enough to reduce the cache as necessary if you need more than 16 GB for working memory. I have not had a problem with it thus far.

Profile Marius
Project administrator
Project developer
Project scientist
Avatar
Send message
Joined: 29 Jun 15
Posts: 427
Credit: 4,276
RAC: 0
Message 21355 - Posted: 30 Apr 2017, 12:31:43 UTC - in response to Message 21349.
Last modified: 30 Apr 2017, 12:33:01 UTC

Hello David.
I am not sure that my answer is right but i think it is.
I have 32GB ram too and have RAMdisk (4GB) where i install BOINC manager AND VirtualBox software. When i check the task of C@H in virtualbox the virtual machines are stored in this RAMdisk and i think nothing is in my HDD. But i am not sure that this is 100% right.
I hope that someone from C@H will answer better than me.


That's correct, currently no disk writes are performed from inside the VM except for the result files, as everything is inside a RAMdisk. However, at some point this will likely change as it can make the RAM requirement quite high for Docker images that are pretty big.

David
Send message
Joined: 17 Apr 17
Posts: 6
Credit: 3,763,928
RAC: 16,596
Message 21396 - Posted: 4 May 2017, 4:43:52 UTC

'Twould be nice if I could see that graphically. There are tons of things we Linux/UNIX folks could handle better if we could see each section graphically. I personally don't have the talent for writing those.

Message boards : Technical Support : how to determine resrources virtualbox/cosmo are being used