RE: Weird Sysmaster behaviour
Posted in 2005
Harry,
If your table is not fragmented, you may have reached the
maximum number of pages for a tablespace -- 16.7 million. Trying to
exceed 16.7 million pages in a tablespace will produce the extents error
you received. Use oncheck -pT to verify how many pages your table is
using. Also, make sure you run queries in sysmaster with dirty read
isolation level.
-Dave
David Buchholz
Sr. DBA
Vital Processing Services
-----Original Message-----
From: owner-informix-list@iiug.org [mailto:owner-informix-list@iiug.org]
On Behalf Of HarryH
Sent: Sunday, November 27, 2005 10:06 PM
To: informix-list@iiug.org
Subject: Weird Sysmaster behaviour
The original problem was that a data load got this error:
271: Could not insert new row into the table. 136: ISAM error: nomore extents
I assumed that it had run out of space. But onstat -d (grepped for the
particular DBSPACE):
Dbspaces
address number flags fchunk nchunks flags owner name
2bacc318 7 1001 9 12 N informix eom_dbs
Chunks
address chk/dbs offset size free bpages flags pathname
2b9e5a90 9 7 0 1000000 6529 PO- eom_chk1.dbf
2b9e5d30 12 7 0 1000000 28884 PO- eom_chk2.dbf
2b9e5e10 13 7 0 1000000 146417 PO- eom_chk3.dbf
2b9e5ef0 14 7 0 1000000 185384 PO- eom_chk4.dbf
2b9f2830 15 7 0 250000 26983 PO- eom_chk5.dbf
2b9f29f0 17 7 0 1000000 66326 PO- eom_chk6.dbf
2b9f2e50 22 7 0 1000000 32814 PO- eom_chk7.dbf
2b9f31d0 26 7 0 1024000 49900 PO- eom_chk8.dbf
2b9f39b0 35 7 0 1024000 277394 PO- eom_chk9.dbf
2b9f3d30 39 7 0 1024000 300435 PO- eom_chk10.dbf
2c5c8018 41 7 0 128000 5162 PO- eom_chk11.dbf
2c9d3a30 42 7 0 256000 79660 PO- eom_chk12.dbf
So there's a fair bit of space, and some chunks with lots of space.
So then I went to a script I have which shows me the tables with
extents > 20 because I though that the offending table had too many
extents. After a lots of problems with the script I eventually opened
DBACCESS and did this:
select count(*) from sysextentsIt took over 20 minutes to return 6491.
I've just done it again and it again took over 20 minutes to return
6492.
The full script does group by and having and order by and normally runs
in 1-2 minutes. So something very odd is happening when such a simple
query takes 20 minutes. And while the server does chug away, it's not
highly utilised. Here's sar 5 5:
15:57:21 %usr %sys %wio %idle
15:57:26 29 1 0 70
15:57:31 26 1 0 72
15:57:36 30 2 0 68
15:57:41 33 1 0 65
15:57:46 33 4 0 63
Average 30 2 0 68
Anyone got any ideas? This is well outside my area of knowledge.
Thanks in advance for any help you might give,
Chris Bullivant
sending to informix-list