SCSI Disk layer performance
Quoted 2 lines · Christoph Hellwig
What kernel tree do you use? If you're looking for decent scsi performance use linux 2.6 or the SuSE/RH vendor trees. Stock Linux 2.4
^^^^^^
_Enterprise_ kernels, RHEL or SLES.
Fedora Core kernel is, more or less, a plain kernel.org.
I'm runnig RHEL 2.4.21-9.EL kernel and it's _much better_ than any 2.4.xx kernel.org. I could call it 2.5 because it's a mix of 2.4 and 2.6 ;-)
Signature · 1 line
Software is like sex, it's better when it's bug free.
Quoted 6 lines · Xose Vazquez Perez
Quoted 2 lines · Christoph Hellwig
What kernel tree do you use? If you're looking for decent scsi performance use linux 2.6 or the SuSE/RH vendor trees. Stock Linux 2.4
Quoted 7 lines
^^^^^^_Enterprise_ kernels, RHEL or SLES.
Fedora Core kernel is, more or less, a plain kernel.org.I'm runnig RHEL 2.4.21-9.EL kernel and it's
_muchbetter_than any 2.4.xx kernel.org. I could call it 2.5 because it's a mix of 2.4 and 2.6 ;-)
The 2.4.21-9EL might have clever things backported into it, but it is still missing essential things that can make a difference in the block layer, like an anticipatory I/O schedule. My impression is that all 2.4 kernels use the Linus Elevator. That works well with moderate SMP loads, but it does not perform well on my large-ish Hardware RAID0 1.1Tbyte ext3 partition on a Power Vault 220S with a Dell PERC4 host adapter. The 2.6.1 does work a lot more better in that sense, giving me an average read of 90 Mbytes/sec as opposed to 60+somethingMbytes/sec I used to get before with 2.4.21-9ELsmp.
The new I/O schedulers (let alone driver maturity issues) are the way to go for maximum performance! I won't place -for the moment- a 2.6 on a production grade system, but in a couple of releases, I will put 2.4 in the museum :-) with respect to SCSI I/O performance.
Regards,
Signature · 5 lines
-- George B. Magklaras Computer Systems Engineer/UNIX Systems Administrator The Biotechnology Centre of Oslo
Quoted 10 lines · George Magklaras
The 2.4.21-9EL might have clever things backported into it, but it is still missing essential things that can make a difference in the block layer, like an anticipatory I/O schedule. My impression is that all 2.4 kernels use the Linus Elevator. That works well with moderate SMP loads, but it does not perform well on my large-ish Hardware RAID0 1.1Tbyte ext3 partition on a Power Vault 220S with a Dell PERC4 host adapter. The 2.6.1 does work a lot more better in that sense, giving me an average read of 90 Mbytes/sec as opposed to 60+somethingMbytes/sec I used to get before with 2.4.21-9ELsmp.
Quoted 4 lines
The new I/O schedulers (let alone driver maturity issues) are the way to go for maximum performance! I won't place -for the moment- a 2.6 on a production grade system, but in a couple of releases, I will put 2.4 in the museum :-) with respect to SCSI I/O performance.
How does the anticipatory scheduler compare to the deadline scheduler on your system?
What types of IO are you doing?
-- Patrick Mansfield