Hi, Very interesting suggestions as I'm contemplating a Supermicro-based server for my work as well, but probably in a lower budget as a backup store for an aging Thumper (not as its superior replacement).
Still, I have a couple of questions regarding your raidz layout recommendation. On one hand, I've read that as current drives get larger (while their random IOPS/MBPS don't grow nearly as fast with new generations), it is becoming more and more reasonable to use RAIDZ3 with 3 redundancy drives, at least for vdevs made of many disks - a dozen or so. When a drive fails, you still have two redundant parities, and with a resilver window expected to be in hours if not days range, I would want that airbag, to say the least. You know, failures rarely come one by one ;) On another hand, I've recently seen many recommendations that in a RAIDZ* drive set, the number of data disks should be a power of two - so that ZFS blocks/stripes and those of of its users (like databases) which are inclined to use 2^N-sized blocks can be often accessed in a single IO burst across all drives, and not in "one and one-quarter IO" on the average, which might delay IOs to other stripes while some of the disks in a vdev are busy processing leftovers of a previous request, and others are waiting for their peers. In case of RAIDZ2 this recommendation leads to vdevs sized 6 (4+2), 10 (8+2) or 18 (16+2) disks - the latter being mentioned in the original post. Did you consider this aspect or test if the theoretical warnings are valid? Thanks, //Jim Klimov -- This message posted from opensolaris.org _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
