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Re: SATA RAID5 speed drop of 100 MB/s

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From: Jeff Garzik
Subject: Re: SATA RAID5 speed drop of 100 MB/s
Date: Saturday, June 23, 2007 - 3:43 pm

Carlo Wood wrote:

IN THEORY, RAID performance should /increase/ due to additional queued 
commands available to be sent to the drive.  NCQ == command queueing == 
sending multiple commands to the drive, rather than one-at-a-time like 
normal.

But hdparm isn't the best test for that theory, since it does not 
simulate the transactions like real-world MD device usage does.

We have seen buggy NCQ firmwares where performance decreases, so it is 
possible that NCQ just isn't good on your drives.

	Jeff


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Messages in current thread:
SATA Harddisk speed drop of 100 MB/s, Carlo Wood, (Wed Jun 20, 3:48 pm)
Re: SATA Harddisk speed drop of 100 MB/s, Jeff Garzik, (Wed Jun 20, 4:06 pm)
Re: SATA Harddisk speed drop of 100 MB/s, Arjan van de Ven, (Wed Jun 20, 8:36 pm)
Re: SATA Harddisk speed drop of 100 MB/s, Carlo Wood, (Fri Jun 22, 9:21 am)
Re: SATA Harddisk speed drop of 100 MB/s, Henrique de Moraes H ..., (Fri Jun 22, 2:17 pm)
Re: SATA Harddisk speed drop of 100 MB/s, Carlo Wood, (Fri Jun 22, 2:27 pm)
Re: SATA RAID5 speed drop of 100 MB/s, Carlo Wood, (Fri Jun 22, 2:44 pm)
Re: SATA RAID5 speed drop of 100 MB/s, Carlo Wood, (Fri Jun 22, 2:48 pm)
Re: SATA Harddisk speed drop of 100 MB/s, Henrique de Moraes H ..., (Fri Jun 22, 6:31 pm)
Re: SATA Harddisk speed drop of 100 MB/s, Carlo Wood, (Fri Jun 22, 7:59 pm)
Re: SATA RAID5 speed drop of 100 MB/s, Carlo Wood, (Fri Jun 22, 8:54 pm)
Re: SATA RAID5 speed drop of 100 MB/s, Tejun Heo, (Fri Jun 22, 11:22 pm)
Re: SATA RAID5 speed drop of 100 MB/s, Jeff Garzik, (Sat Jun 23, 12:03 am)
Re: SATA RAID5 speed drop of 100 MB/s, Tejun Heo, (Sat Jun 23, 12:54 am)
Re: SATA RAID5 speed drop of 100 MB/s, Carlo Wood, (Sat Jun 23, 5:53 am)
Re: SATA Harddisk speed drop of 100 MB/s, Andrew Morton, (Sat Jun 23, 10:29 am)
Re: SATA RAID5 speed drop of 100 MB/s, Bartlomiej Zolnierki ..., (Sat Jun 23, 10:30 am)
Re: SATA Harddisk speed drop of 100 MB/s, Jeff Garzik, (Sat Jun 23, 3:21 pm)
Re: SATA RAID5 speed drop of 100 MB/s, Jeff Garzik, (Sat Jun 23, 3:43 pm)
Re: SATA RAID5 speed drop of 100 MB/s, Michael Tokarev, (Sun Jun 24, 4:58 am)
Re: SATA RAID5 speed drop of 100 MB/s, Dr. David Alan Gilbert, (Sun Jun 24, 5:59 am)
Re: SATA RAID5 speed drop of 100 MB/s, Justin Piszcz, (Sun Jun 24, 7:21 am)
Re: SATA RAID5 speed drop of 100 MB/s, Michael Tokarev, (Sun Jun 24, 8:48 am)
Re: SATA RAID5 speed drop of 100 MB/s, Michael Tokarev, (Sun Jun 24, 8:52 am)
Re: SATA RAID5 speed drop of 100 MB/s, Justin Piszcz, (Sun Jun 24, 9:59 am)
Re: SATA RAID5 speed drop of 100 MB/s, Carlo Wood, (Sun Jun 24, 3:07 pm)
Re: SATA RAID5 speed drop of 100 MB/s, Mark Lord, (Sun Jun 24, 4:46 pm)
Re: SATA RAID5 speed drop of 100 MB/s, Patrick Mau, (Sun Jun 24, 5:23 pm)
Re: SATA Harddisk speed drop of 100 MB/s, Lennart Sorensen, (Mon Jun 25, 8:18 am)
Re: SATA Harddisk speed drop of 100 MB/s, Carlo Wood, (Mon Jun 25, 9:04 am)
Re: SATA RAID5 speed drop of 100 MB/s, Phillip Susi, (Thu Jul 5, 3:12 pm)