Advfs showfile perf 1% on EVA Units

[Ivan Ferreira]

Hi Manager/Experts

I have advfs domains on a EVA Units. Advfs domain/filesets never has been defragmented. When I run showfile on a oracle datafile, i have the following result:

showfile trp_datl01a.dbf

Id Vol PgSz Pages XtntType Segs SegSz I/O Perf File
32.8003 1 16 723329 simple ** ** async 1% trp_datl01a.dbf

We are NOT having performance problems, i'm just doing a general performance verification.

The 1% perf usualy means that the file is very fragmented.

Questions:

Is showfile accurate?

Can I defragment the oracle domain with the dabase active (with low system activity)?

The defragment utility should increase the performance of the datafile, so that when I run showfile again would have more performance displayed?

Thanks in advance.

[Han Pilmeyer · Accepted solution]

The showfile "Perf" indicator is meaningless and should be ignored.

You can run defragment with the database active. However there are a few issues with defragment and vfast, so it would be good if you were on V5.1B BL26. I'm not currently aware of any problems "damaging" the domain, so it should be safe from that point of view.

You can use "showfile -x" on the individual files in the domain to see how badly fragmented those are.

[Venkatesh BL]

How many extents are shown for the file in the showfile output?

[Alexey Borchev]

>>We are NOT having performance problems, i'm just doing a general performance verification.
Oracle I/O is wery fragmented (~ random IO with size = DB_BLOCK_SIZE), so You will likeky not notice any performance degradation. But on continuouse disk access operations (full table scans, backups) You will likely see performance difference.

The defragment command has option to show You fragmentation status of the file domain (not the file).

[Ivan Ferreira]

Thanks for all responses. Now, here is my problem. If I run the defragment -nv to check the fragmentation of the domain I get:

# defragment -nv kml_dmn
defragment: Gathering data for domain 'kml_dmn'
Current domain data:
Extents: 4112
Files w/extents: 95
Avg exts per file w/exts: 43.28
Aggregate I/O perf: 100%
Free space fragments: 256
<100K <1M <10M >10M
Free space: 0% 0% 0% 100%
Fragments: 37 170 3 46


Perf 100%

But when i run showfile on files IN the domain:

# showfile *

Id Vol PgSz Pages XtntType Segs SegSz I/O Perf File
2d.8003 1 16 768129 simple ** ** async 33% HEC_DATM02a.dbf
59.8002 1 16 6401 simple ** ** async 25% jde_dats01a.dbf
5c.8003 1 16 390273 simple ** ** async 6% kml_dath01a.dbf
5b.8002 1 16 70273 simple ** ** async 33% kml_dath81a.dbf
26.8003 1 16 537729 simple ** ** async 20% kml_datl01a.dbf
27.8003 1 16 1600129 simple ** ** async 5% kml_datl02a.dbf
28.8003 1 16 1881729 simple ** ** async 1% kml_datl03a.dbf
22.8003 1 16 729729 simple ** ** async 3% kml_datl04a.dbf
23.8003 1 16 76929 simple ** ** async 33% kml_datl05a.dbf
57.8003 1 16 208001 simple ** ** async 6% kml_datl06a.dbf
60.8001 1 16 540801 simple ** ** async 2% kml_datl07a.dbf
24.8003 1 16 495489 simple ** ** async 33% kml_datm01a.dbf
25.8003 1 16 377729 simple ** ** async 8% kml_datm02a.dbf
15.8003 1 16 192001 simple ** ** async 0% kml_dats01a.dbf
f.8003 1 16 64001 simple ** ** async 3% kml_dats02a.dbf
5d.8002 1 16 195201 simple ** ** async 14% kml_idxh01a.dbf
61.8001 1 16 192129 simple ** ** async 4% kml_idxl06a.dbf
1a.8003 1 16 35969 simple ** ** async 6% max_dats01a.dbf
1c.8003 1 16 10241 simple ** ** async 100% tmp_dats01a.dbf

showfile -x * |egrep "dbf|extentCnt"
2d.8003 1 16 768129 simple ** ** async 33% HEC_DATM02a.dbf
extentCnt: 2
59.8002 1 16 6401 simple ** ** async 25% jde_dats01a.dbf
extentCnt: 3
5c.8003 1 16 390273 simple ** ** async 6% kml_dath01a.dbf
extentCnt: 17
5b.8002 1 16 70273 simple ** ** async 33% kml_dath81a.dbf
extentCnt: 2
26.8003 1 16 537729 simple ** ** async 20% kml_datl01a.dbf
extentCnt: 4
27.8003 1 16 1600129 simple ** ** async 5% kml_datl02a.dbf
extentCnt: 19
28.8003 1 16 1881729 simple ** ** async 1% kml_datl03a.dbf
extentCnt: 71
22.8003 1 16 729729 simple ** ** async 3% kml_datl04a.dbf
extentCnt: 29
23.8003 1 16 76929 simple ** ** async 33% kml_datl05a.dbf
extentCnt: 2
57.8003 1 16 208001 simple ** ** async 6% kml_datl06a.dbf
extentCnt: 16
60.8001 1 16 540801 simple ** ** async 2% kml_datl07a.dbf
extentCnt: 45
24.8003 1 16 495489 simple ** ** async 33% kml_datm01a.dbf
extentCnt: 2
25.8003 1 16 377729 simple ** ** async 8% kml_datm02a.dbf
extentCnt: 12
15.8003 1 16 192001 simple ** ** async 0% kml_dats01a.dbf
extentCnt: 257
f.8003 1 16 64001 simple ** ** async 3% kml_dats02a.dbf
extentCnt: 29
5d.8002 1 16 195201 simple ** ** async 14% kml_idxh01a.dbf
extentCnt: 6
61.8001 1 16 192129 simple ** ** async 4% kml_idxl06a.dbf
extentCnt: 24
1a.8003 1 16 35969 simple ** ** async 6% max_dats01a.dbf
extentCnt: 16
1c.8003 1 16 10241 simple ** ** async 100% tmp_dats01a.dbf
extentCnt: 1

Low performance.


I don't know if I should take into account the defragment command output or the showfile command output.

[Victor Semaska_3]

Ivan,

I usually use the defragment output. The 'Avg exts per file w/exts:' in particular. For a domain with no fragmentation this field will have a value of 1.00. The more fragmented a domain gets the higher the value.

Your output shows this field with a value of 43.28 which to me indicates that domain is very fragmented.

Vic

[Venkatesh BL]

You could try "migrate" on a multi-volume domain, to defragement a file.