From: Justin Piszcz Subject: Re: mdadm software raid + ext4, capped at ~350MiB/s limitation/bug? Date: Sun, 28 Feb 2010 15:03:00 -0500 (EST) Message-ID: References: <20100228080100.092c24c2@notabene.brown> <4B89B44A.70005@tmr.com> <170fa0d21002280633x2ea6a281tf53996834c46d831@mail.gmail.com> <4B8A8D68.1020809@tmr.com> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Cc: Mike Snitzer , Neil Brown , linux-kernel@vger.kernel.org, linux-raid@vger.kernel.org, linux-ext4@vger.kernel.org, Alan Piszcz To: Bill Davidsen Return-path: Received: from lucidpixels.com ([75.144.35.66]:35785 "EHLO lucidpixels.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1031964Ab0B1UDD (ORCPT ); Sun, 28 Feb 2010 15:03:03 -0500 In-Reply-To: <4B8A8D68.1020809@tmr.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Sun, 28 Feb 2010, Bill Davidsen wrote: > Justin Piszcz wrote: >> >> >> On Sun, 28 Feb 2010, Mike Snitzer wrote: >> >>> On Sun, Feb 28, 2010 at 4:45 AM, Justin Piszcz >>> wrote: >> >> [ .. ] >> >>> >>> How did you format the ext3 and ext4 filesystems? >>> >>> Did you use mkfs.ext[34] -E stride and stripe-width accordingly? >>> AFAIK even older versions of mkfs.xfs will probe for this info but >>> older mkfs.ext[34] won't (though new versions of mkfs.ext[34] will, >>> using the Linux "topology" info). >> >> Yes and it did not make any difference: >> http://lkml.org/lkml/2010/2/27/77 >> >> Incase anyone else wants to try too, you can calculate by hand, or if you >> are in a hurry, I found this useful: >> http://busybox.net/~aldot/mkfs_stride.html >> >> I believe there is something fundamentally wrong with ext4 when performing >> large sequential I/O when writing, esp. after Ted's comments. >> >> Justin. >> >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-raid" in >> the body of a message to majordomo@vger.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html >> > I'm going to have to do some testing now, I just tested ext4 against the raw > speed of the device (single device test) and they were quite close to > identical. I'm going to order one more drive to bring my test setup up to > five devices, and do some testing on how it behaves. > > More later. Thanks, let me know how it goes, I see the same thing, on a single hard drive, there is little difference between EXT4 and XFS: http://permalink.gmane.org/gmane.linux.kernel/955357 However, when multiple disks are involved, it is a different story. Justin.