* smart raid1 reads?
@ 2003-06-20 1:14 Nicholas Leippe
2003-06-20 3:56 ` Why I couldn't turn the DMA mode on ? bmoon
0 siblings, 1 reply; 2+ messages in thread
From: Nicholas Leippe @ 2003-06-20 1:14 UTC (permalink / raw)
To: linux-raid
Hi,
I searched the archives, and the last time this was mentioned was in 2001, and
no response was ever given.
In a raid0, of course, reads pull off every disk in parallel, thus performance
scales with # of disks.
However, with raid1, it does not do this--it always reads from just one half
of the mirror. Why doesn't it read from both halves of the mirror in
parallel? I would expect it to, and would expect raid1 to perform similar to
raid0 for reads.
I have observed this with 2.4.18 and 2.4.20 thru at least 21rc2.
Nick
please cc
^ permalink raw reply [flat|nested] 2+ messages in thread
* Why I couldn't turn the DMA mode on ?
2003-06-20 1:14 smart raid1 reads? Nicholas Leippe
@ 2003-06-20 3:56 ` bmoon
0 siblings, 0 replies; 2+ messages in thread
From: bmoon @ 2003-06-20 3:56 UTC (permalink / raw)
To: linux-raid
I rebuilt kernel with 2.4.20 with patch ,
then I can not set the DMA mode on my
hda drive.
> hdparm -d 1 /dev/hda
/dev/hda:
setting using_dma to 1(on)
HDIO_SET_DMA failed: Operation not permitted
using_dma = 0 (off)
I have no problem with old REDHAT7.1.
From my .config,
CONFIG_BLK_DEV_IDEDMA_PCI = y
# CONFIG_BLK_DEV_IDEDMA_FORCED
CONFIG_IDEDMA_PCI_AUTO = y
CONFIG_BLK_IDEDMA = y
Any comment or suggestion?
Bo
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