Messages in this thread | | | Date | Tue, 16 Dec 2003 13:04:12 -0800 (PST) | From | Andre Hedrick <> | Subject | Re: raid0 slower than devices it is assembled of? |
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Size is MB, BlkSz is Bytes, Read, Write, and Seeks are MB/secd . -T
File Block Num Seq Read Rand Read Seq Write Rand Write Dir Size Size Thr Rate (CPU%) Rate (CPU%) Rate (CPU%) Rate (CPU%) ------- ------ ------- --- ----------- ----------- ----------- ----------- . 2018 4096 1 244.7 53.6% 8.847 2.26% 88.04 41.7% 5.594 7.16% . 2018 4096 2 281.6 65.6% 11.04 3.53% 89.86 69.5% 6.645 9.78% . 2018 4096 4 235.6 64.3% 13.91 4.45% 88.26 96.2% 7.647 12.7% . 2018 4096 8 231.2 68.0% 15.91 5.34% 85.59 105.% 7.557 10.3%
Two channel, Six drives, three per channel.
U320 with 15K U160 drives in a soft Raid 0.
Andre Hedrick LAD Storage Consulting Group
On Tue, 16 Dec 2003, Andre Hedrick wrote:
> > Helge, > > Reads you may gain on writes only if all devices are on single ended mode. > Both pATA and pSCSI suck wind in writes, pSCSI should smoke pATA on reads. > It is all a matter of the physical protocol on the wire. > > Only in SATA/SAS will you even reach close to ideal world. > > Cheers, > > Andre Hedrick > LAD Storage Consulting Group > > On Tue, 16 Dec 2003, Helge Hafting wrote: > > > jw schultz wrote: > > > > > No Linux [R]AID improves sequential performance. How would > > > reading 65KB from two disks in alternation be faster than > > > reading continuously from one disk? > > > > > Raid-0 is ideally N times faster than a single disk, when > > you have N disks. Because you can read continuously from N > > disks instead of from 1, thereby N-doubling the bandwith. > > > > Wether the current drivers manages that is of course another story. > > > > Helge Hafting > > > > > > - > > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > > the body of a message to majordomo@vger.kernel.org > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > Please read the FAQ at http://www.tux.org/lkml/ > > > > - > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ >
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