On Sat, 13 Dec 2008, Dak wrote: > What do you think about this architecture? Could the gateway be a > bottleneck? Do you have any other ideas or recommendations?
You will need to have redundancy somewhere to avoid possible data loss. If redundancy is in the backend, then you should be protected from individual disk failure, but it is still possible to lose the entire pool if something goes wrong with the frontend pool. Unless you export individual backend server disks (or several volumes from a larger pool) using iSCSI the problem you may face is the resilver time if something goes wrong. If the size of the backend storage volume is too big, then the resilver time will be excessively long. You don't want to have to resilver up to 2.5TB since that might take days. The ideal solution will figure out how to dice up the storage in order to minimize the amount of resilvering which much take place if something fails. For performance you want to maximize the number of vdevs. Simple mirroring is likely safest and most performant for your headend server with raidz or raidz2 on the backend servers. Unfortunately, simple mirroring will waste half the space. You could use raidz on the headend server to minimize storage space loss but performance will be considerably reduced since writes will then be ordered and all of the backend servers will need to accept the write before the next write can proceed. Raidz will also reduce resilver performance since data has to be requested from all of the backend servers (over slow iSCSI) in order to re-construct the data. If you are able to afford it, you could get rid of the servers you were planning to use as backend storage and replace them with cheap JBOD storage arrays which are managed directly with ZFS. This is really the ideal solution in order to maximize performance, maximize reliability, and minimize resilver time. 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
