swap_pager: indefinite wait
asossi at dotcom.ts.it
Mon Nov 17 09:17:59 PST 2008
Paul B. Mahol wrote:
> On 11/17/08, Sossi Andrej <asossi at dotcom.ts.it> wrote:
>> I manage a www (apache), database (postgresql) and e-mail (qmail) with
>> about 100 Internet domains.
>> We recently purchased a DELL MD3000i server with data access through
>> ISCSI protocol.
>> I installed a new server with FreeBSD 7.0 compiled kernel with ISCSI
>> (v. 2.1) and SCHED_ULE scheduler.
>> The server's local disk configuration is:
>> 512 MB /
>> 1024 MB SWAP
>> 254 MB / var
>> 2048MB / var/ qmail
>> 512 MB /tmp
>> ~ 70 GB /usr
>> The apache data (/usr/local/www), postgre (/usr/local/pgsql) and qmail
>> (/usr/local/vpopmail) are instead on the partition on ISCSI. After
>> installing all the necessary softwares I tested the machine as mail
>> server for a one domain and everything worked fine for 2-3 days.
>> I wanted to test the correct functioning of qmail and of the
>> reading/writing on ISCSI. On the end of testing I decided to transfer
>> all of data (www, DB and e-mail) on the FreeBSD 7.0. I compressed all
>> the data on the original server (on tar.gz format). I transferred them
>> on the new server and started to decompress the files. Www data have
>> been decompressed correctly on the ISCSI disk. But while the messages
>> were being decompressed (~80GB of tar.gz) and all the DB were being
>> restored, the server crashed.
> Which application were used for decompression?
I use this command:
tar -xvzf filename.tar.gz (for file decompression as root)
psql -f filename.sql postgres (for restore all databases)
>> The error shown was:
>> swap_pager: indefinite wait buffer: bufobj: 0, blkno: 31, size: 4096
> I believe this can happen any time when to much of swap partition is used.
> If this sort of thing happens often, review memory management of application(s)
> that is causing such scenario, if that is application fault - you have
> two choices:
> get more RAM (this may not always help) or use another application.
> Increasing swap partition will not help much ....
During decompression i sometimes monitor the system with command top and
I don't see the system use swap at all, but I didn't monitor constantly.
If the problem is caused by tar, what choices do i have to transport
files from original server to another quickly?
>> This message repeated every 30 seconds.
>> While restarting with the single user mode I checked there wasn't any
>> message after the crash in /var/log/messages.
>> I think 1GB of swap should be enough, since with this configuration on
>> FreeBSD 5.5 everything worked for over 270 days without reboot.
>> The local disks are 2 of ~80GB in RAID 1 (mirror) with Gmirror
>> before installing FreeBSD I tested the 2 disks with the badblocks
>> software on Slackware which didn't find any r/w error.
>> Can somebody help me understand why the system crashed this way or how
>> to avoid future crash?
>> It's a production server and I can't afford an out-of-service or data loss.
>> Thank you very much and kind regards
Thank for your reply.
DotCom Information technology
Via Biancospino, 9
34151 - Opicina (TS)
tel: +39 040 2158191
fax: +39 040 0641954
E-mail: asossi at dotcom.ts.it
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