Re: [zfs-discuss] Disabling disks' write-cache in J4200 with ZFS?

[Todd E. Moore]

I'm working with a group that wants to commit all the way to disk every single write - flushing or bypassing all the caches each time.  The fsync() call will flush the ZIL.  As for the disk's cache, if given the entire disk, ZFS enables its cache by default.  Rather than ZFS having to issue the flush command to the disk we want to disable this cache and avoid the step altogether Richard Elling wrote: Todd E. Moore wrote: I want to disable write cache on the disk drives in our J4200 JBODs so that fsync() actually writes to disk, not just to the cache on the drive. ZFS will do this for you, via the way the ZIL works. Neil explains it pretty well at http://blogs.sun.com/perrin/entry/the_lumberjack I did this using 'format -e', but it displays a warning about the drive being part of a zpool and also it says that the change is not permanent.   Is 'format -e' the right way to do this with ZFS?  Is there no way to make it permanent? In general, you don't need to do this.  ZFS will send the cache flush command to the disks as needed. -- richard -- Todd E. Moore Sun Microsystems Incorporated 443.516.4002 AIM: toddmoore72462

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