Curious re: High CPU IOWAIT Times

[Steve Beschakis]

Just added a FreeNAS box to my home network and I'm very happy with this great open-source storage solution. I over-built the server using a fast proc and a 16G pot of ECC RAM. I'm sure it could perform just as well without the quad-core cpu, but it was on sale..heh. Anyway, I'm currently migrating a large volume of data from smaller drives across the network to the new 11TB (!) volume, and during copies, Zabbix sends me alerts of the type below.
I'm not sure how to interpret the alerts, or whether they refer to a single core (of the four). During the copy operations, the system is perfectly useable and data transfers are transparent, so I guess I don't care. Just wondering if the alert--which is a pre-established, unedited trigger that Zabbix created by default when setting up the monitoring environent for a Linux server--is anything to be concerned about.

--Thanks

Code:

Trigger: Disk I/O is overloaded on Zabbix server
Trigger status: PROBLEM
Trigger severity: Warning
Trigger URL:

Item values:

1. CPU iowait time (Zabbix server:system.cpu.util[,iowait]): 25.61 %
2. *UNKNOWN* (*UNKNOWN*:*UNKNOWN*): *UNKNOWN*
3. *UNKNOWN* (*UNKNOWN*:*UNKNOWN*): *UNKNOWN*

 

[cyberjock]

Ok. So few things:

1. Server specs
2. How are you moving this data?(CIFS, AFP, FTP, etc.)
3. What is this Zabbix. I've never heard of it, but i'm confused on why you'd be discussing it on FreeNAS. I'm fairly sure its not part of FreeNAS, so I don't know how you'd be using it for monitoring.
4. Any other error messages?

 

[Steve Beschakis]

Oh, sorry, Zabbix is just a monitoring / alerting app...sort of a standard open-source enterprise solution. It's total overkill for a small home network, but I use it at the office, so I thought it would be useful to play with at home. Anyway, I mount the share via NFS from my main Linux system. NFS is the only service apart from Smartmon that I enabled through the FreeNAS admin GUI. Mainly, I was wondering about options for CPU optmizing under FreeNAS. Maybe the default setup isn't taking full advantage of the multi-core proc. I should probably do more reading. Thing is, the FreeNAS setup was so straightforward and quick, I haven't had a chance to dig deeply into the docs. Thanks for any input in the meantime. :)

MainBoard:
SUPERMICRO MBD-X9SCL-F-O LGA 1155 Intel C202 Micro ATX Intel Xeon E3 Server Motherboard

CPU:
Intel Xeon E3-1230 V2 Ivy Bridge 3.3GHz (3.7GHz Turbo) 4 x 256KB L2 Cache 8MB L3 Cache LGA 1155 69W Quad-Core Server Processor BX80637E31230V2

RAM:
16GB Total, 2X:

Storage:
16 TB Total (RAIDZ-2 usable) - 6X:
WD Red WD40EFRX 4TB IntelliPower 64MB Cache SATA 6.0Gb/s 3.5" NAS Internal Hard Drive -Bulk

Ok. So few things:

1. Server specs
2. How are you moving this data?(CIFS, AFP, FTP, etc.)
3. What is this Zabbix. I've never heard of it, but i'm confused on why you'd be discussing it on FreeNAS. I'm fairly sure its not part of FreeNAS, so I don't know how you'd be using it for monitoring.
4. Any other error messages?

 

[jgreco]

Perhaps - just a thought here - your disks are busy.

It is unclear why you'd expect that a default alert for a generic Linux/FreeBSD/etc server would be appropriate for a fileserver. PEBCAK. A fileserver having a low iowait percentage is neither shocking nor noteworthy.

 

[Steve Beschakis]

OK, nm. I think my question was misunderstood, but it doesn't matter because I just solved all my perf issues in another way. I added a 5-port dumb gigabit switch to my 10/100mbps router to boost transfer speed between internal network nodes and the NAS box and voila! at least 8X increase in speed. Happy! I do have one other question:
For some reason, I was permission blocked on some of the files I transferred, and so I just pulled up the console from within the FreeNAS gui and made the changes, umounted / remounted the share from the client and everything's cool. I thought I had the permissions setup with the right recursion in the initial setup, but I prolly didn't understand how this aspect of the thing works. No problem, as long as it's OK to make as-needed changes to files and directories like I did.
FreeNAS is fun! Here's a "before and after" Zabbix graph of the gigabit upgrade:
https://lh4.googleusercontent.com/-...AAAAAAATM/JSzWZgbwHMc/w1453-h880-no/gb-sw.png

 

[cyberjock]

First:

If a 10/100 hub/switch was your first problem, that's a serious oversight by someone trying to setup a FreeNAS box.

Second, you should be making a new thread as changing the subject isn't appropriate.

Third,

I see no question there... at all.