From: Eric Sandeen <sandeen@sandeen.net>
To: Chris Murphy <lists@colorremedies.com>
Cc: "xfs@oss.sgi.com" <xfs@oss.sgi.com>
Subject: Re: What is a recommended XFS sector size for hybrid (512e) advanced format hard drives?
Date: Tue, 06 Jan 2015 23:31:44 -0600 [thread overview]
Message-ID: <54ACC4C0.2030802@sandeen.net> (raw)
In-Reply-To: <CAJCQCtS8M5w76bzr4TzB9CQo+tTOwsfAu8+x5h7p9W_RMfEgFA@mail.gmail.com>
On 1/6/15 1:55 PM, Chris Murphy wrote:
> What's sectsz= used for? Historically this would be sectsz=512,
> bsize=4096 before AF hard drives appeared. So is sectsz used for
> optimizing sub blocksize changes? e.g. if only 50 bytes needs
> changing, the fs doesn't need to read modify and write the entire 4096
> block, just change the affected sector?
Nope, filesystem data blocks are always fully written, but the sector
size is i.e. the minimum _log_ IO size.
+/*
+ * The xfs_buftarg contains 2 notions of "sector size" -
+ *
+ * 1) The metadata sector size, which is the minimum unit and
+ * alignment of IO which will be performed by metadata operations.
+ * 2) The device logical sector size
+ *
+ * The first is specified at mkfs time, and is stored on-disk in the
+ * superblock's sb_sectsize.
+ *
+ * The latter is derived from the underlying device, and controls direct IO
+ * alignment constraints.
-Eric
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next prev parent reply other threads:[~2015-01-07 5:31 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-01-05 0:56 What is a recommended XFS sector size for hybrid (512e) advanced format hard drives? Hillel Lubman
2015-01-05 3:52 ` Stan Hoeppner
2015-01-06 2:23 ` Hillel Lubman
2015-01-06 3:21 ` Stan Hoeppner
2015-01-06 4:01 ` Hillel Lubman
2015-01-06 8:35 ` Matthias Schniedermeyer
2015-01-06 17:02 ` Eric Sandeen
2015-01-06 19:05 ` Chris Murphy
2015-01-06 19:23 ` Eric Sandeen
2015-01-06 19:42 ` Chris Murphy
2015-01-06 19:55 ` Chris Murphy
2015-01-07 5:31 ` Eric Sandeen [this message]
2015-01-07 6:01 ` Chris Murphy
2015-01-07 5:17 ` Hillel Lubman
2015-01-07 5:30 ` Eric Sandeen
2015-01-07 5:36 ` Hillel Lubman
2015-01-07 6:06 ` Chris Murphy
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