Hello Good People, As we are already using the drives in udma mode, I wondered if either of the settings mentioned here might help & what the implications may be: http://www.redhat.com/support/wpapers/redhat/ext3/tuning.html The server handles a lot of email & several hundred web sites too. Would "data=writeback option" help or not (to reduce journalling activities)? Anything else we can do? Thanks in advance. Regards, Nico Morrison nico.morrison@micronicos.com ___________________________________________ Micronicos Limited - London, UK. Tel: +44 20 8870 8849 Fax: +44 20 8870 5290 ___________________________________________ From: Andrew Morton [mailto:akpm@digeo.com] Sent: 04 February 2003 02:20 To: Nico Morrison Cc: ext3-users@redhat.com; nico.morrison@micronicos.com Subject: Re: On very different journalling activity on 2 servers. Nico Morrison <nico.morrison@micronicos.com> wrote: > > Hello Folks, > > We have 2 (identical hardware) busy public 2U rack servers, both have > several hundred users & peak email (for example) deliveries at 300/5min > during the daytime. > > Both servers run RAID1 over 2 EIDE disk drives. > > One server is fine - it never has problems - it is running RH7.3 and CPU > loads are normal. > > The other server has constant disk activity & kjournald at CPU load of > 50/60/70% most of the time! this machine is running RH7.2 > > The same processes & loads are on both machines - can anyone tell me why one > machine should have so much kjournald activity & the other not? > > Is it a difference between 7.2 & 7.3 or must it be another factor? Usually, this is due to IDE drives running in PIO mode and not DMA mode. > How can I find out? > Look at the output of `hdparm -i': # hdparm -i /dev/hda /dev/hda: Model=Maxtor 5T040H4, FwRev=TAH71DP0, SerialNo=T4J0N9BC Config={ Fixed } RawCHS=16383/16/63, TrkSize=0, SectSize=0, ECCbytes=57 BuffType=DualPortCache, BuffSize=2048kB, MaxMultSect=16, MultSect=16 CurCHS=16383/16/63, CurSects=16514064, LBA=yes, LBAsects=80043264 IORDY=on/off, tPIO={min:120,w/IORDY:120}, tDMA={min:120,rec:120} PIO modes: pio0 pio1 pio2 pio3 pio4 DMA modes: mdma0 mdma1 mdma2 UDMA modes: udma0 udma1 *udma2 udma3 udma4 udma5 AdvancedPM=yes: disabled (255) WriteCache=enabled Drive conforms to: ATA/ATAPI-6 T13 1410D revision 0: 1 2 3 4 5 6 See the "*" next to UDMA2? This disk is doing DMA. You can manually force DMA mode, which is considered risky. Or upgrade the kernel, perhaps. _______________________________________________ Ext3-users@redhat.com https://listman.redhat.com/mailman/listinfo/ext3-users
