Description of Problem: Version-Release number of selected component (if applicable): 2.4.7-10 How Reproducible: ALWAYS Steps to Reproduce: 1. Install RedHat 7.2 2. Boot (Ensure MPS Spec 1.1 in Bios. MPS 1.4 causes this Asus CUV-4X dual PIII 933 to hang on ISAPNP scanning for devices on boot up.) 3. Be disappointed with poor (udma-33 equivalent drive I/O performance.) Actual Results: Going to INIT 1 and then running hdparm -t /dev/hda or hdparm -t /dev/hdb produces results of 20.08 for HDA and 24.37 for HDB, which are an IBM 40 GB ATA 100 drive and a Maxtor 100 GB ATA 100 drive respectively. Expected Results Disk I/O data transfer rates were expected to be in the 30 MB/sec to 60 MB/sec range. A number of Dell Optiplex machines at this site have UDMA 33 controllers and manage more than 30 MB/sec. Additional Information: cat /proc/ide/via ----------VIA BusMastering IDE Configuration---------------- Driver Version: 3.23 South Bridge: VIA vt82c686b Revision: ISA 0x40 IDE 0x6 Highest DMA rate: UDMA100 BM-DMA base: 0xd800 PCI clock: 33MHz Master Read Cycle IRDY: 0ws Master Write Cycle IRDY: 0ws BM IDE Status Register Read Retry: yes Max DRDY Pulse Width: No limit -----------------------Primary IDE-------Secondary IDE------ Read DMA FIFO flush: yes yes End Sector FIFO flush: no no Prefetch Buffer: yes no Post Write Buffer: yes no Enabled: yes yes Simplex only: no no Cable Type: 40w 40w -------------------drive0----drive1----drive2----drive3----- Transfer Mode: UDMA UDMA DMA UDMA Address Setup: 30ns 30ns 30ns 30ns Cmd Active: 90ns 90ns 90ns 90ns Cmd Recovery: 30ns 30ns 30ns 30ns Data Active: 90ns 90ns 90ns 90ns Data Recovery: 30ns 30ns 30ns 30ns Cycle Time: 60ns 60ns 120ns 60ns Transfer Rate: 33.3MB/s 33.3MB/s 16.5MB/s 33.3MB/s [root@liberty1 ide]# pwd /proc/ide [root@liberty1 ide]# It seems clear from the above (as well as the attached dmesg output) that the maximum transfer rate is 100 MB/s, and that all I am getting is 33.3MB/s for all drives (except the CD Burner at HDC.)
VIA controllers sometimes misdetect a udma33 cable as a udma66 cable, and as a result we have to not trust the chipset. You can tell the kernel you have safe cables by passing "ide0=ata66" on the kernel commandline (edit grub.conf for that and add it to the end of the line with vmlinuz in it)
Created attachment 37282 [details] dmessg output detailing problem and showing sample from another machine that UDMA66/UDMA 100 *SHOULD* work....