On Jul 2, 2011, at 6:39 AM, Edward Ned Harvey wrote: >> From: zfs-discuss-boun...@opensolaris.org [mailto:zfs-discuss- >> boun...@opensolaris.org] On Behalf Of Edward Ned Harvey >> >> Conclusion: Yes it matters to enable the write_cache. > > Now the question of whether or not it matters to use the whole disk versus > partitioning, and how to enable the write_cache automatically on sliced > disks: > > I understand that different people have had different results based on which > hardware and which OS rev they are using. So if this matters to you, you'll > just need to check for yourself. But here is what I found: > > On a Sun(Oracle) X4270 and solaris 11 express, my behavior is pretty much as > the man page describes. If I create a pool using the whole disks, then the > write_cache is enabled automatically. When I destroy a pool, the > write_cache is returned to its previous (disabled) state. When I create a > pool using slices of the disks, then the write_cache is not automatically > enabled.
Yes, this is annoying. In NexentaStor, we have a property that manages the write cache policy on a per-device basis. > > I would like to know: Is there some way to enable the write cache > automatically on specific devices? I have a script that will enable the > write_cache on all the devices (just a simple wrapper around format -f) and > of course I can make it run at startup, or on a cron job, etc. But I'd like > to know if there's a more native way to achieve that end result. I would say change the way it compiles, but you are stuck without source for Solaris. > > I have one really specific reason to care about automatically enabling the > write_cache on sliced disks: > > All the disks in the system are large disks. (2T). The OS only needs a few > G, so we install the OS into mirrored slices. The rest of the disk is > sliced and added to the storage pool. The default behavior in this > situation is to disable write_cache on the first few disks. Sounds like a reasonable request to me. Maybe Oracle will accept an RFE? -- richard _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
