Hello, freebsd-geom.
On FreeBSD 8.2-RELEASE long periods of «Suspend time» have been detected
- tens of seconds - while reading large files from gjournal partition:
For example:
root@mail [/var/tmp]# du -h /var/tmp/access.log
8.3G /var/tmp/access.log
root@mail[/var/tmp]# dd if=/var/tmp/access.log of=/dev/null
17417604 +1 records in
17417604 +1 records out
8917813440 bytes transferred in 50.760701 secs (175,683,418 bytes/sec)
root@mail[/var/tmp] # grep \/var/var/log/messages
...
Mar 27 14:48:08 mail kernel: GEOM_JOURNAL [1]: Suspend time of /var:
0.018053s
Mar 27 14:48:18 mail kernel: GEOM_JOURNAL [1]: Msync time of /var:
0.020182s
Mar 27 14:49:03 mail kernel: GEOM_JOURNAL [1]: Sync time of /var: 0.022150s
Mar 27 14:49:03 mail kernel: GEOM_JOURNAL [1]: Suspend time of /var:
45.187463s
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Mar 27 14:49:13 mail kernel: GEOM_JOURNAL [1]: Msync time of /var:
0.014821s
Mar 27 14:49:13 mail kernel: GEOM_JOURNAL [1]: Sync time of /var: 0.017499s
Mar 27 14:49:13 mail kernel: GEOM_JOURNAL [1]: Suspend time of /var:
0.016974s
...
At the time when «Suspend time» = 45.187463s, all operations on the disk
(gjournal partition) are blocked. All processes (htttp, squid, sshd,
pop3d, imapd, and even login) are waiting for the expiration of this
time. And only after that continue to operate normally.
This does not happen if not only read but also simultaneously write to
the partition with gjournal.
(dd if=/var/tmp/access.log of=/var/tmp/a.log or cp /var/tmp /access.log
/var/spool/uucppublic)
Partion with gjournal is located on a hardware RAID 10 - driver aac.
I put a ordinary sata disk in the computer and create a gjournal
partition on it..
On the sata drive it worked fine.
So I guess that the problem is in the driver aac.
Could it be so because the aac driver does not support BIO_FLUSH?
PS.
root@mail[/var/tmp]# gjournal list
Geom name: gjournal 609973015
ID: 609973015
Providers:
1. Name: ad6p4.journal
Mediasize: 456084396032 (425G)
Sectorsize: 512
Mode: r0w0e0
Consumers:
1. Name: ad6p4
Mediasize: 494739102208 (461G)
Sectorsize: 512
Mode: r1w1e1
Jend: 494739101696
Jstart: 456084396032
Role: Data, Journal
Geom name: gjournal 2757859993
ID: 2757859993
Providers:
1. Name: aacd0p5.journal
Mediasize: 498216205824 (464G)
Sectorsize: 512
Mode: r1w1e2
Consumers:
1. Name: aacd0p5
Mediasize: 536870912000 (500G)
Sectorsize: 512
Mode: r1w1e1
Jend: 536870911488
Jstart: 498216205824
Role: Data, Journal
Server uses 12 G memory.
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