SUMMARY: swap size max and file transfer speed

From: Kevin Metzger <>
Date: Wed May 07 2003 - 09:43:14 EDT
Thanks for all the quick responces to
Chang, Johnny
Steven Hill
Darren Dunham
Rajeev Jain
Faulconer, Steven M.
Steven Hill
Ric Anderson
Florendo, Jay Jay
Rich Teer
Jay Lessert
trey valenta

The answer was a bad Cisco GBIC.  And since packets were never reaching this
NIC, there were no errors reported on the interface.

The questions about the swap size limit, concensious was no, in 64bit OS,
there is no limit. ("Well, no bigger than 1TB, for sure.  :-)")

Lots of suggestions that RAID might will cuase slower writes than reads or
that there might be a RAID problem.  RAID was not involved in this case and I
should have mentioned that the slow down was as 1000 times slower or more.

Several suggestions about commands used to diagnose the problem including
iostat -xtc 1
netstat -i 5
try using tools like iostat, vmstat , mpstat , sar and vxstat
vmstat 15
/usr/sbin/swap -s
iostat -pD 15

One commentary specific to the V880 disk subsystem performance can be pretty
poor.  He mentioned that the firmware upgrade helped a little, but still didn't
get into the expected range.

One comment about UFS write throttling and while I found a doc with the
/etc/system entries to adjust or disable it, I didn't impliment those changes
yet, so I cannot speak to their effectiveness.  They are:
* for Solaris 9
set ufs_ufs_LW = 8388608
set ufs_ufs_HW = 16777216

* to disable
set ufs:ufs_WRITES = 0

or disable using adb:
# adb -wk

Kevin Metzger

Recieved Tue, 6 May 2003, from Kevin Metzger:

-Date: Tue, 6 May 2003 17:44:20 -0400 (EDT)
-From: Kevin Metzger <>
-To: sunmanagers mailing list <>
-Subject: swap size max and file transfer speed
-Is there a limit on the size that one swap file can be?
-Other reasons why moving files to the V880 is slow and moving files off the
-V880 is fast?
-I'm working with a V880 with 2 CPU and 4 G mem, planning on 8 G mem, and
-6x72G fiber drives.  Moving files to the V880 is _slow_, moving files from the
-V880 is fast.  One fella here wondered if the 17G swap file were the cause.  
-I'm googling like a mad man on this and when I asked this group when I was
-setting this up, those who replied said 2-4 times mem and 17G is 4x now and 2x
-soon.  There were no caviots about having only one file.
-Summary to follow.
-Kevin Metzger
-sunmanagers mailing list
sunmanagers mailing list
Received on Wed May 7 09:43:08 2003

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