vm.kmem Size Error and Prefetch

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Yellowbeard

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I have just built a machine for FreeNAS using an ASUS P5Q-E, Pentium 650, 6GB of RAM, and 4 x 2TB Hitachi 5K300s attached to the ICH10-R in AHCI mode. AFAIK, I have it set up correctly. ZFS-RAIDZ, I built the volume, created a share, enabled CIFS and it works but it's unstable. It keeps crashing with the errors shown in the attached picture.

I am a complete and total noob at this sort of thing even though I have been running FreeNAS since 2006. Any input on how I go about fixing this? I see the recomendations to tune the mem size but I have NO CLUE how or where to do that.

Also, prefetch is disabled. Is it beneficial to enable it?

Thanks in advance for any assistance.
 

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Yellowbeard

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So far so good, Chris nailed it! I'll keep this thread updated if anything changes but I think we're good.

Thanks!
 

jenksdrummer

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I had a similar problem with FreeNAS 7.3 using ZFS - it was considered experimental then, and it showed with errors like the one you posted. 8.0 is definately the right move...though some of the extra features of 7.3 haven't made it yet, they are being worked in! :)
 

esamett

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+1. the 64 bit build is more robust for zfs and memory management - even for the same amount of ram. the only reason imho to use 32 bit build is if you are using a 32 bit cpu
 

NiceTry

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I'm having same problem with 3GHz Pentium 4 Prescott, 2GB RAM, ZFS RAIDZ, 4-1GB SATA drives. Will AMD version help here too?
 

ohnename

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Only if your P4 is 64bit.
If it is a socket 478 it is only 32bit, if it is a socket 775 you have to check exactly what modell you have, not all are supporting 64bit.
 

NiceTry

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My CPU does not support 64-bit. Can anyone tell me why this situation occurs? Are there any configuration work-arounds? Seems odd to fail in such a fundamental way. Do I need a 64-bit capable CPU to support ZFS?
 

ohnename

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A 64bit system with 4GB or more RAM is better if you want to use ZFS, a 32bit system with 2GB RAM will be much slower. I got about 20MB/s CIFS performance with a similar config.
To fix your problem with prefetch and set vm.kmem_size & vm.kmem_size_max you should edit the /boot/loader.conf file.
 

NiceTry

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Thanks ohnename. I looked at the loader.conf file and there is no mention of vm.kmem or prefetch parameters. What lines should I add for 32-bit mode? I'm not a FreeBSD expert by any means...

Before it crashed, a speed test with an 8GB file yielded ~40MB/s rates. Also, hardly any of the physical memory was being used, according to FreeNAS system reporting and TOP running on the server console.
 

NiceTry

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Thanks ohnename. It's been decades since I used ed... Had to get retrained.

I added the lines as you suggested and will be testing the result. The explanation of how the cpu loading can back up buffers and eventually cause a panic made sense to me as I watched the loading on a long set of file transfers. It got to almost 3. My conclusion is that I need to get a better processor to keep up with the demand.

Thanks again.
 

NiceTry

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Crash! This time its:
"kmem_malloc(XXXXXXX): kmem map too small: 518000640 total allocated" replicated on the screen at least six or seven times."
"panic: Cannot Dump. Device not defined or not available."

I should use a 64-bit processor and the AMD64 version, eh?
 

NiceTry

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Up and running with E4600 2.4GHz Core 2 Duo, 4GB RAM, 4-1TB drives in RAIDZ. Using amd-64 version of v8.0. So far, so good but the reporting does not seem to be working. Is there anything that needs to be turned on or is there something I need to check is running to get reporting on-line? Do I need special settings on my browser?

Any help would be appreciated. I feel I'm so close to success here...
 

NiceTry

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Stopped collectd, cleared reporting history, restarted collectd and ran save_rrds script. Reporting seems to be working now.
 
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