On Apr 14, 2010, at 2:42 AM, Ragnar Sundblad wrote: > > On 12 apr 2010, at 19.10, Kyle McDonald wrote: > >> On 4/12/2010 9:10 AM, Willard Korfhage wrote: >>> I upgraded to the latest firmware. When I rebooted the machine, the pool >>> was back, with no errors. I was surprised. >>> >>> I will work with it more, and see if it stays good. I've done a scrub, so >>> now I'll put more data on it and stress it some more. >>> >>> If the firmware upgrade fixed everything, then I've got a question about >>> which I am better off doing: keep it as-is, with the raid card providing >>> redundancy, or turn it all back into pass-through drives and let ZFS handle >>> it, making the Areca card just a really expensive way of getting a bunch of >>> SATA interfaces? >>> >> >> AS one of the other posters mentioned there may be a third way that >> might give you something close to "the best of both worlds". >> >> Try using the Areca card to make 12 single disk RAID 0 LUNs, and then >> use those in ZFS. >> I'm not sure of the definition of 'passthrough', but if it disables any >> battery backed cache that the card may have, then by setting up 12 HW >> RAID LUNs instead, you it should give you an improvement by allowing the >> Card to cache writes. >> >> The one downside of doing this vs. something more like 'jbod' is that if >> the controller dies you will need to move the disks to another Areca >> controller, where as with 12 'jbod' connections you could move them to >> pretty much any controller you wanted. > > And that if you use the write cache in the controller and the controller > dies, parts of your recently written data is only in the dead controller, > and your pool may be more or less corrupt and may have to be rolled back > a few versions to be rescued or may be not rescuable at all. > This may may not be acceptable.
There was successful recovery of what seemed to be result of lost cache on Areca controller, see this thread: http://opensolaris.org/jive/thread.jspa?threadID=109007 it was manual recovery, but these days we have 'zpool import -fFX <poolname>' that would do the same in a lot more user-fiendly manner. -- regards victor _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
