Hello again! 2010/9/24 Gary Mills <mi...@cc.umanitoba.ca>: > On Fri, Sep 24, 2010 at 12:01:35AM +0200, Alexander Skwar wrote:
>> Yes. I was rather thinking about RAIDZ instead of mirroring. > > I was just using a simpler example. Understood. Like I just wrote, we're actually now going to use mirroring, so that I've got "some space" from site A and an identical amount from site B. Got to correct my other posting - I don't know if they are doing fail over on the storage side. Need to find out. BTW: To refer back to my original question: If disk management is to be ignored (because SAN does it for us), are there any differences (even if internally) if I use a slices on "disk" devices, compared to whole disk, as far as ZFS is concerned? Of course, it's understood that it's generally a rather bad idea to make a RAIDZ from 3 slices on the same disk device, if this actually represents one spindle. Not to be recommended, at least not for production, at least not generally. But what about a SAN environment? How do 3 "pseudo devices" of 400 GB each differ compared to one huge 1200 GB lump? Even though it's not really an issue for me anymore, since we're going to do mirroring from 2 sites, it's a question which I find interesting ;) From my limited knowledge, I'd say that there is *NO* difference. >> Anyway. Without redundancy, ZFS cannot do recovery, can >> it? As far as I understand, it could detect block level corruption, >> even if there's not redundancy. But it could not correct such a >> corruption. >> >> Or is that a wrong understanding? > > That's correct, but it also should never happen. "should" ;) > >> If I got the gist of what you wrote, it boils down to how reliable >> the SAN is? But also SANs could have "block level" corruption, >> no? I'm a bit confused, because of the (perceived?) contra- >> diction to the Best Practices Guide? :) > > The real problem is that ZFS was not designed to run in a SAN > environment, that is one where all of the disk management and > sufficient redundancy reside in the storage device on the SAN. ZFS > certainly can't do any disk management in this situation. Yes, disk management of course can't be done. > Error > detection and correction is still a debatable issue, one that quickly > becomes exceedingly complex. When I've got a mirror in ZFS, I've already got the needed redundancy that ZFS requires, so that it can do its magic, don't I? Thanks, Alexander -- ↯ Lifestream (Twitter, Blog, …) ↣ http://alexs77.soup.io/ ↯ ↯ Chat (Jabber/Google Talk) ↣ a.sk...@gmail.com , AIM: alexws77 ↯ _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
