From: Adams Kevin J (kevin.adams@PHS.COM)
Date: Thu Feb 13 2003 - 14:32:26 EST
Mounir,
Your fcs0 adapter settings for num_cmd_elems and max_xfer_size are at max,
so not much you can do there.
However, your hdisk queue_depth might be a little low, with the range being
1-256. A redbook I once read suggessted 75, but I'm unable to find it to
verify.
We have a 2109 switched SAN, with 4 path vpaths and 2 6227 FC adapters per
host, and according to NMON, we max out at 18 MBps per vpath. We little or
no i/o wait though.
We have your exact settings for the adapters and hdisk. We had to lower the
hdisk queue_depth back down from 75 to 20 because we were overrunning the
host adapter num_cmd_elems, and this was done at ML08 without a PTF to apply
in emergency mode when the adapters froze. The temp fix was to raise the
adapters num_cmd_elems to max, and lower hdisk queue_depth back to default
of 20. It's been fixed via PTF, just can't make any more changes right now.
At a TSM class at Userblue, the speaker said they have found the host FC
adapters to be the limiting bottleneck. You have only 2?
Kevin Adams
-----Original Message-----
From: mounir.stambouli [mailto:mounir.stambouli@LAPOSTE.NET]
Sent: Thursday, February 13, 2003 7:32 AM
To: aix-l@Princeton.EDU
Subject: [aix-l] disk I/O throughput
Hello,
We've got an AIX 5.1 box with FC adapters directly connected
to ESS FC ports (no SAN). The theoretical throughput is 100+
MBPS but nmon reports that we're getting no more than 8
MBPS !!! I have paste the output of lsattr of various devices.
ESS volumes are configured as RAID5 seen through 2 paths for
each vpath.
Is there any additional config to be done ?
Where should I look on the ESS ?
Thanks in advance,
Mounir
U62CTSM001:/ lsattr -El fcs0
bus_intr_lvl 51 Bus interrupt
level False
intr_priority 3 Interrupt
priority False
bus_io_addr 0xec00 Bus I/O
address False
bus_mem_addr 0xe0020000 Bus memory
address False
lg_term_dma 0x200000
N/A True
max_xfer_size 0x1000000 Maximum Transfer
Size True
num_cmd_elems 1024 Maximum number of COMMANDS to queue
to the adapter True
pref_alpa 0x1 Preferred
AL_PA True
sw_fc_class 2 FC Class for
Fabric True
init_link al INIT Link
flags True
U62CTSM001:/ lsattr -El fscsi0
scsi_id 0x1 Adapter SCSI ID False
attach al How this adapter is CONNECTED False
sw_fc_class 3 FC Class for Fabric True
U62CTSM001:/ lsattr -El hdisk13
scsi_id 0xef N/A
True
lun_id 0x5029000000000000 N/A
True
location N/A
True
ww_name 0x5005076300c68efe N/A
False
pvid none Physical volume identifier
False
q_type simple Queuing TYPE
True
queue_depth 20 Queue DEPTH
True
start_timeout 180
eout 60 READ/WRITE time out value
True
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