On May 5, 2011, at 2:58 PM, Brandon High wrote: > On Wed, May 4, 2011 at 8:23 PM, Edward Ned Harvey > >> Or if you're intimately familiar with both the guest & host filesystems, and >> you choose blocksizes carefully to make them align. But that seems >> complicated and likely to fail. > > Using a 4k block size is a safe bet, since most OSs use a block size > that is a multiple of 4k. It's the same reason that the new "Advanced > Format" drives use 4k sectors.
Yes, 4KB block sizes are replacing the 512B blocks of yesteryear. However, the real reason the HDD manufacturers headed this way is because they can get more usable bits per platter. The tradeoff is that your workload may consume more real space on the platter than before. TANSTAAFL. The trick for best performance and best opportunity for dedup (alignment notwithstanding) is to have a block size that is smaller than your workload. Or, don't bring a 128KB block to a 4KB block battle. For this reason, the default 8KB block size for a zvol is a reasonable choice, but perhaps 4KB is better for many workloads. -- richard _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
