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>To: Russ Rew <address@hidden> >From: "Stonie R. Cooper" <address@hidden> >Subject: Re: 20020730: The significance of pbuf_flush messages. >Organization: Planetary Data >Keywords: pbuf_flush-problem Hi Stonie, > No more pbuf_flush logs on ldm 5.2 . . . . > > There was a post by someone earlier about the incapatibility of ext3 and > Linux with the ldm queue . . . but I had assumed it dealt specifically with > ext3. > > As we normally deal with very large file systems, I use reiserfs. It's > great, it's fast, it's easy to deal with. > > But it also doesn't play well with the ldm queue. > > . . . . after roughly a week of analysis . . . > > The kernel interrupts on that single file system (I dedicate a single 2GB > file system to a 1.7GB ldm queue - no other files are on that file system) > where ~100 times that of the LVM based reiserfs that was getting a lot more > data. Even with a dual P-III, I was slowing everything way down, especially > services tied to that filesystem. > > I haven't tried other jfs's . . . but considering the low complexity of the > single file system, I was silly not to make it a ext2 in the first place. > > I have not gotten a single pbuf_flush message since shoving back to ext2 - > and I just tuned out the regularly scheduled fsck's with a tune2fs -c -1 on > that file system, so I can enjoy not having uninvited fsck'ers. Sorry, > couldn't resist. > > I generally stick on a problem . . . and wear it down. Thanks for the information on this problem. Here's my summary of what you learned, let me know if I got it wrong: - On a Linux platfrom, use a simple ext2 file system partition for the LDM product queue, since reiserfs or ext3 will cause performance problems, with symptom lots of pbuf_flush messages. - For even better performance, turn off the periodic file system checking with "tunefs -c -1". I'm still not sure if the patch we provided to LDM 5.2 is also needed, but we're including it in 5.2.1 anyway ... --Russ