This might be unrelated, but along similar lines .
I've also heard that the risk for unexpected failure of your pool is higher if/when you reach 100% capacity. I've heard that you should always create a small ZFS filesystem within a pool, and give it some reserved space, along with the filesystem that you actually plan to use in your pool. Anyone care to offer any comments on that? From: zfs-discuss-boun...@opensolaris.org [mailto:zfs-discuss-boun...@opensolaris.org] On Behalf Of Edward Ned Harvey Sent: Friday, April 02, 2010 5:23 PM To: zfs-discuss@opensolaris.org Subject: [zfs-discuss] To slice, or not to slice Momentarily, I will begin scouring the omniscient interweb for information, but I'd like to know a little bit of what people would say here. The question is to slice, or not to slice, disks before using them in a zpool. One reason to slice comes from recent personal experience. One disk of a mirror dies. Replaced under contract with an identical disk. Same model number, same firmware. Yet when it's plugged into the system, for an unknown reason, it appears 0.001 Gb smaller than the old disk, and therefore unable to attach and un-degrade the mirror. It seems logical this problem could have been avoided if the device added to the pool originally had been a slice somewhat smaller than the whole physical device. Say, a slice of 28G out of the 29G physical disk. Because later when I get the infinitesimally smaller disk, I can always slice 28G out of it to use as the mirror device. There is some question about performance. Is there any additional overhead caused by using a slice instead of the whole physical device? There is another question about performance. One of my colleagues said he saw some literature on the internet somewhere, saying ZFS behaves differently for slices than it does on physical devices, because it doesn't assume it has exclusive access to that physical device, and therefore caches or buffers differently . or something like that. Any other pros/cons people can think of? And finally, if anyone has experience doing this, and process recommendations? That is . My next task is to go read documentation again, to refresh my memory from years ago, about the difference between "format," "partition," "label," "fdisk," because those terms don't have the same meaning that they do in other OSes. And I don't know clearly right now, which one(s) I want to do, in order to create the large slice of my disks.
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