NightBird wrote:
On Fri, 26 Jun 2009, Richard Elling wrote:
All the tools I have used show no IO problems. I
think the problem is
memory but I am unsure on how to troubleshoot it.
Look for latency, not bandwidth. iostat will show
latency at the
device level.
Unfortunately, the effect may not be all that obvious
since the disks
will only be driven as hard as the slowest disk and
so the slowest
disk may not seem much slower.
Bob
--
Bob Friesenhahn
bfrie...@simple.dallas.tx.us,
http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,
http://www.GraphicsMagick.org/
____________________________________________
zfs-discuss mailing list
zfs-discuss@opensolaris.org
http://mail.opensolaris.org/mailman/listinfo/zfs-discu
ss
I checked the output of iostat. svc_t is between 5 and 50, depending on when
data is flushed to the disk (CIFS write pattern). %b is between 10 and 50.
%w is always 0.
Example:
device r/s w/s kr/s kw/s wait actv svc_t %w %b
sd27 31.5 127.0 935.9 616.7 0.0 11.9 75.2 0 66
This is a slow disk. Put your efforts here.
sd28 5.0 0.0 320.0 0.0 0.0 0.1 18.0 0 9
This tells me disks are busy but I do not know what they are doing? are they
spending time seeking, writting or reading?
I also review some ARC stats. Here is the output.
ARC Efficency:
Cache Access Total: 199758875
Cache Hit Ratio: 74% 148652045 [Defined State for
buffer]
Cache Miss Ratio: 25% 51106830 [Undefined State for
Buffer]
REAL Hit Ratio: 73% 146091795 [MRU/MFU Hits Only]
Data Demand Efficiency: 94%
Data Prefetch Efficiency: 15%
CACHE HITS BY CACHE LIST:
Anon: --% Counter Rolled.
That is interesting... but only from a developer standpoint.
Most Recently Used: 22% 33843327 (mru) [
Return Customer ]
Most Frequently Used: 75% 112248468 (mfu) [
Frequent Customer ]
Most Recently Used Ghost: 3% 4833189 (mru_ghost) [
Return Customer Evicted, Now Back ]
Most Frequently Used Ghost: 22% 33831706 (mfu_ghost) [
Frequent Customer Evicted, Now Back ]
It seems to me that mfu_ghost being at 22%, I may need a bigger ARC.
Is ARC also designed to work with large memory foot prints (128GB for example
or higher)? Will it be as efficient?
Caching isn't your problem, though adding memory may hide the
real problem for a while. You need faster disk.
-- richard
_______________________________________________
zfs-discuss mailing list
zfs-discuss@opensolaris.org
http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
