Re: [zfs-discuss] Q: zfs log device
I've also suggested this in the past, but I think the end result was that it was pointless: If you have sync writes, the client does not get a reply until the data is on disk. So a SSD drive makes a huge difference. If you have async writes, the client gets a reply as soon as the server has the data, before it gets to disk. So the disk speed makes no difference to response time. -- This message posted from opensolaris.org ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] Q: zfs log device
True, but the ZIL is designed to only hold a small amount of data anyway, so I'm not sure the cost of the ZIL device would be less than the equivalent RAM for the sizes we're talking about. There may be a few cases that would benefit, but I don't think there are enough that Sun would put the effort into making the change. -- This message posted from opensolaris.org ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] Q: zfs log device
On Tue, 30 Jun 2009, John Hoogerdijk wrote: i've setup a RAIDZ2 pool with 5 SATA drives and added a 32GB SSD log device. to see how well it works, i ran bonnie++, but never saw any io's on the log device (using iostat -nxce) . pool status is good - no issues or errors. any ideas? Try using direct i/o (the -D flag) in bonnie++. You'll need at least version 1.03e. Regards, markm ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] Q: zfs log device
On Wed, 1 Jul 2009, Mark J Musante wrote: On Tue, 30 Jun 2009, John Hoogerdijk wrote: i've setup a RAIDZ2 pool with 5 SATA drives and added a 32GB SSD log device. to see how well it works, i ran bonnie++, but never saw any io's on the log device (using iostat -nxce) . pool status is good - no issues or errors. any ideas? Try using direct i/o (the -D flag) in bonnie++. You'll need at least version 1.03e. If this -D flag uses the Solaris directio() function, then it will do nothing for ZFS. It only works for UFS and NFS. Bob -- Bob Friesenhahn bfrie...@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/ GraphicsMagick Maintainer,http://www.GraphicsMagick.org/ ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] Q: zfs log device
Mark J Musante wrote: On Tue, 30 Jun 2009, John Hoogerdijk wrote: i've setup a RAIDZ2 pool with 5 SATA drives and added a 32GB SSD log device. to see how well it works, i ran bonnie++, but never saw any io's on the log device (using iostat -nxce) . pool status is good - no issues or errors. any ideas? Try using direct i/o (the -D flag) in bonnie++. You'll need at least version 1.03e. Or you could export the filesystem via NFS and run any file creation/write workload on an NFS client; that should generate a large amount of log activity thanks to the synchronous writes that the NFS server must issue to honour its obligations to the NFS client. -- jason.ozol...@anu.edu.au ANU Supercomputer Facility Leonard Huxley Bldg 56, Mills Road Ph: +61 2 6125 5449 Australian National University Fax: +61 2 6125 8199 Canberra, ACT, 0200, Australia ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] Q: zfs log device
John Hoogerdijk wrote: so i guess there is some porting to do - no O_DIRECT in solaris... anyone have bonnie++ 1.03e ported already? For your purposes, couldn't you replace O_DIRECT with O_SYNC as a hack? If you're trying to benchmark the log device, the important thing is to generate synchronous writes, and the zero-copy aspect of O_DIRECT is less important, no? -- jason.ozol...@anu.edu.au ANU Supercomputer Facility Leonard Huxley Bldg 56, Mills Road Ph: +61 2 6125 5449 Australian National University Fax: +61 2 6125 8199 Canberra, ACT, 0200, Australia ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
