From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from relay.sgi.com (relay2.corp.sgi.com [137.38.102.29]) by oss.sgi.com (Postfix) with ESMTP id B3C6F7F4E for ; Tue, 26 Nov 2013 00:15:11 -0600 (CST) Received: from cuda.sgi.com (cuda2.sgi.com [192.48.176.25]) by relay2.corp.sgi.com (Postfix) with ESMTP id 9C5D5304053 for ; Mon, 25 Nov 2013 22:15:11 -0800 (PST) Received: from ipmail06.adl6.internode.on.net (ipmail06.adl6.internode.on.net [150.101.137.145]) by cuda.sgi.com with ESMTP id 7IRy7psni3KxDTqk for ; Mon, 25 Nov 2013 22:15:09 -0800 (PST) Date: Tue, 26 Nov 2013 17:14:59 +1100 From: Dave Chinner Subject: Re: ARC-1120 and MD very sloooow Message-ID: <20131126061458.GM8803@dastard> References: <1385118796.8091.31.camel@bews002.euractiv.com> <528FBBE5.80404@hardwarefreak.com> <1385369796.2076.16.camel@bews002.euractiv.com> <5293EF32.9090301@hardwarefreak.com> <20131126025210.GL8803@dastard> <52941C5D.1000305@hardwarefreak.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <52941C5D.1000305@hardwarefreak.com> List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: xfs-bounces@oss.sgi.com Sender: xfs-bounces@oss.sgi.com To: Stan Hoeppner Cc: Jimmy Thrasibule , Linux RAID , "xfs@oss.sgi.com" On Mon, Nov 25, 2013 at 09:58:21PM -0600, Stan Hoeppner wrote: > On 11/25/2013 8:52 PM, Dave Chinner wrote: > ... > > sunit/swidth is in filesystem blocks, not sectors. Hence > > sunit is 1MB, swidth = 2MB. While it's not quite correct > > (su=512k,sw=1m), it's not actually a problem... > > Well that's what I thought as well, and I was puzzled by the 8 blocks > value for the log sunit. So I double checked before posting, and 'man > mkfs.xfs' told me > > sunit=value > This is used to specify the stripe unit for a RAID device > or a logical volume. The value has to be specified in > 512-byte block units. > > So apparently the units of 'sunit' are different depending on which XFS > tool one is using. No they don't. sunit as a mkfs input value is determined by 512 byte units. The output is given in units of "blks" i.e. the log block size: $ mkfs.xfs -N -l sunit=64 /dev/vdb .... log =internal log bsize=4096 blocks=12800, version=2 = sectsz=512 sunit=8 blks, lazy-count=1 Which is given by the "bsize=4096" variable and so are, in this case, 4k in size. input = 64 * 512 bytes = 8 * 4096 bytes = output Remember, you can specify su rather than sunit, and they are specified in sectors, filesystem blocks or bytes, and the output is still in units of log block size: # mkfs.xfs -N -b size=4096 -l su=8b /dev/vdb .... log =internal log bsize=4096 blocks=12800, version=2 = sectsz=512 sunit=8 blks, lazy-count=1 # mkfs.xfs -N -l su=32k /dev/vdb .... log =internal log bsize=4096 blocks=12800, version=2 = sectsz=512 sunit=8 blks, lazy-count=1 IOws, the input units can vary, but the output units are always the same. > That's a bit confusing. And 'man xfs_info' > (xfs_growfs) doesn't tell us that sunit is given in filesystem blocks. > I'm using xfsprogs 3.1.4 so maybe these have been corrected since. It might seem confusing at first, but it's actually quite consistent... > > Again, lsunit is in filesystem blocks, so it is 32k, not 4k. And > > yes, the default lsunit when the sunit > 256k is 32k. So, nothing > > wrong there, either. > > So where should I have looked to confirm sunit reported by xfs_info is > in fs block (4KB) multiples, not the in the 512B multiples of mkfs.xfs? Explained above. Cheers, Dave. -- Dave Chinner david@fromorbit.com _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs