On Fri, Jan 29, 2010 at 5:54 AM, Edward Ned Harvey <sola...@nedharvey.com>wrote:
> > Thanks for the responses guys. It looks like I'll probably use RaidZ2 > > with 8 drives. The write bandwidth isn't that great as it'll be a > > hundred gigs every couple weeks but in a bulk load type of environment. > > So, not a major issue. Testing with 8 drives in a raidz2 easily > > saturated a GigE connection on the client and the server side. We'll > > probably link aggregate two GigE ports onto the switch to boost the > > incoming bandwidth. > > > > In response to some of the other questions - drives are SATA drives > > 7200. All connected via a SAS expander backplane onto a machine. CPU > > cycles obviously aren't an issue on a Xeon machine/24Gig memory. We > > considered a SSD ZIL as well but from my understanding it won't help > > much on sequential bulk writes but really helps on random writes (to > > sequence going to disk better). Also, doubt L2ARC/ARC will help that > > much for sequential either. I could be wrong on both counts here so > > please correct me if I'm wrong. > > I believe you're correct on all points. > > The one comment I want to add, as a tangent, is about link aggregation. > You > may already know this, but a lot of people don't, so please forgive me if > I'm saying something obvious. > > When you aggregate links together, say, 4x 1Gb ports, you are of course > increasing the speed & reliability of the network interface, but you don't > get something like a 4Gb port. Instead, you get a link where any one > client > TCP or whatever connection will max out at 1Gb, but the advantage is, while > one client is maxing out at 1Gb, another client can come along and also max > out another 1Gb, and a 3rd client ... and a 4th client ... > > Make sense? Obvious? > > Isn't that basically the same thing...i mean. If you have 4x 1Gb as in your example, can you have 4 clients connected at the same time all over Gb ethernet all getting close to 1Gb/s? Isn't this LIKE having a 4Gb/s connection considering everything ELSE on your network is essentially limited by thier small 1Gb/s connections? Also, doesn't it also provide a level of fault tolerance as well as load balancing? _______________________________________________ > zfs-discuss mailing list > zfs-discuss@opensolaris.org > http://mail.opensolaris.org/mailman/listinfo/zfs-discuss >
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