On Mon, Dec 14, 2009 at 4:04 AM, Jens Elkner <jel+...@cs.uni-magdeburg.de> wrote: > On Sat, Dec 12, 2009 at 04:23:21PM +0000, Andrey Kuzmin wrote: >> As to whether it makes sense (as opposed to two distinct physical >> devices), you would have read cache hits competing with log writes for >> bandwidth. I doubt both will be pleased :-) > > Hmm - good point. What I'm trying to accomplish: > > Actually our current prototype thumper setup is: > root pool (1x 2-way mirror SATA) > hotspare (2x SATA shared) > pool1 (12x 2-way mirror SATA) ~25% used user homes > pool2 (10x 2-way mirror SATA) ~25% used mm files, archives, > ISOs > > So pool2 is not really a problem - delivers about 600MB/s uncached, > about 1.8 GB/s cached (i.e. read a 2nd time, tested with a 3.8GB iso) > and is not contineously stressed. However sync write is ~ 200 MB/s > or 20 MB/s and mirror, only. > > Problem is pool1 - user homes! So GNOME/firefox/eclipse/subversion/soffice > usually via NFS and a litle bit via samba -> a lot of more or less small > files, probably widely spread over the platters. E.g. checkin' out a > project from a svn|* repository into a home takes "hours". Also having > its workspace on NFS isn't fun (compared to linux xfs driven local soft > 2-way mirror).
Flash-based read cache should help here by minimizing (metadata) read latency, and flash-based log would bring down write latency. The only drawback of using single F20 is that you're trying to minimize both with the same device. > > So, seems to be a really interesting thing and I expect at least wrt. > user homes a real improvement, no matter, how the final configuration > will look like. > > Maybe the experts at the source are able to do some 4x SSD vs. 1xF20 > benchmarks? I guess at least if they turn out to be good enough, it > wouldn't hurt ;-) Would be interesting indeed. Regards, Andrey > >> > Jens Elkner wrote: > ... >> >> whether it is possible/supported/would make sense to use a Sun Flash >> >> Accelerator F20 PCIe Card in a X4540 instead of 2.5" SSDs? > > Regards, > jel. > -- > Otto-von-Guericke University http://www.cs.uni-magdeburg.de/ > Department of Computer Science Geb. 29 R 027, Universitaetsplatz 2 > 39106 Magdeburg, Germany Tel: +49 391 67 12768 > _______________________________________________ > zfs-discuss mailing list > zfs-discuss@opensolaris.org > http://mail.opensolaris.org/mailman/listinfo/zfs-discuss > _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
