a) Verify if you have the last microcode for those disks, if not upgrade the microcode level.
to see the actual microcode:
lscfg -vl hdisk* |more
to check if the last go to:
http://techsupport.services.ibm.com/.../download.html
b) Check your network settings.
c) In addition, if its possible to create a striped File System with
an exclusive JFS log where to download the file, go ahead.
To create an exclusive fjslog:
mklv -t jfslog -y ftp_jfslog vgname 1
logform /dev/ftp_jfslog
umount /your_striped_fs
chfs -a log=/dev/ftp_jfslog /your_striped_fs
mount /your_striped_fs
vgname: is the Volume Group that contain the ftp FS.
Note: Remember the emergency FIX for the Remote buffer overflow in ftpd daemon. Look for ftpd.tar.Z in
ftp://aix.software.ibm.com/aix/efixes/security/
Also you can read (at
www.redbooks.ibm.com):
SC23-2365 Chapter:Monitoring and Tuning Disk I/O.
SG24-4989 RS/6000 Performance Tools in Focus
SG24-6184 AIX Performance and System Tuning Study Guide (chapter's 4 and 5)
Examples of portions of text:
a) Striped LV
When a striped logical volume is defined, then two additional
LV attributes are displayed by the lslv command: STRIPE WIDTH
The number of stripes. STRIPE SIZE The fixed size of each
stripe block. Stripe size can be any power of 2 from 4 KB to
128 KB, but it is often set to 64 KB to get the highest levels
of sequential I/O throughput.
b)Chapter 4. Disk I/O performance monitoring tools 127
4.4.4 Highest LVM performance The following general recommendations
can be used for creating logical volumes with high performance demands.
However, keep in mind that when a logical volume is tuned for better
performance, the availability may be impacted.
• No mirroring, which means the number of copies equals one (1).
• If mirroring is required then:
- Write scheduling policy set to parallel.
- Allocation policy set to strict, which means each copy on separate physical volumes.
• Write verification set to no.
• Mirror write consistency (MWC) set to off.
• Intra policies:
- Center: for hot logical volumes
- Middle: for moderate logical volumes
- Edge: for cold logical volumes
• Inter disk allocation policy set to maximum, which mean that read/write operations are
spread among physical volumes. Additional performance improvement can be gained by creating
a striped logical volume. 4.5 LVM and file system monitoring
--------------------------------
To determine if a SCSI adapter is saturated, summarize all the KB/s values for disks
located on the same adapter and compare the sum with the SCSI adapter throughput.
In general, use 70 percent of the SCSI standard throughput rate. Examples of different
SCSI types and their throughput is provided in the following:
• SCSI-1 throughput rate of 3.5 MB/s (70 percent of 5 MB/s)
• SCSI-2 throughput rate of 7 MB/s (70 percent of 10 MB/s)
• Ultra SCSI throughput rate of 28 MB/s (70 percent of 40 MB/s)
• Ultra2 SCSI throughput rate of 56 MB/s (70 percent of 80 MB/s)
----------------------------------
If you want to look for IO contention see:
http://publib16.boulder.ibm.com/pser...d/appAbody.htm
------------------------------
commands:
filemon, fileplace, defragfs, lslv, chlv, reorgvg, ....
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Regards. Hugo.
