Hello Christine, Saturday, December 16, 2006, 12:17:12 AM, you wrote:
CT> Hi, CT> I guess we are acquainted with the ZFS Wikipedia? CT> http://en.wikipedia.org/wiki/ZFS CT> Customers refer to it, I wonder where the Wiki gets its numbers. For CT> example there's a Sun marketing slide that says "unlimited snapshots" CT> contradicted by the the first bullet: CT> 2^48 — Number of snapshots in any file system (2 × 10^14) CT> Is this correct? I belive it is. However 2^48 limit per file system is for every practical purpose virtually no limit, right? So when it comes to marketing I guess they get it right. CT> I want to make a mirrored pool but after creation detach one side of the CT> mirror and run like this indefinitely. Can I do this? I have yet to CT> try it out, just wondering if someone knows the answer right off the bat. Of course you can. However you won't be able to "mount" detached submirror. I guess it should be quite easy to implement if needed (yes, it's needed). CT> Why can't I have a vdev of type concat? A customer says he has hardware CT> RAID-0 and does not want to stripe over stripe. Are there known CT> problems with stripes on stripes, unintentional hotspots maybe? Depends how those stripes on HW array are actually configured and depends on data access pattern. Once you put enough data that more LUNs are used then even with concatenation you'll get into trouble (assuming pathological situation already). But generally if config is done right stripe on stripe shouldn't be a problem at all (rather should give you more performance). By pathological situation I assume config like creating a stripe from some hypers (partitions) each on differen disk, then making another stripe from other hypers on the same disks and then striping between such LUNs on a host. CT> Data checksum is used only to detect bad data, and not to recover data, CT> correct? Just verifying. Depends. If you do only striping in ZFS then you're right (not counting ditto blocks for meta data - however it can be useful). Once you create redundant pool in ZFS then you're not only able to detect bad data but also to correct them on the fly. That's what ZFS does automatically for you. CT> Can I use ZFS specifically with PowerPath? I remember George W. CT> mentioning that PowerPath tries to do something clever and it interfered CT> with ZFS but I can't remember the specifics. In theory it should work. However someone else reported a problem with such a combination and IIRC it was about not exporting all LUN details by PP rather than doing anything clever by PP itself. I hope it was fixed by EMC and if not perhaps it's a good idea to fill in BUG in EMC (maybe I should test it and do it my self - just need some time). CT> Will I be able to I tune the DMU "flush" rate, now set at 5 seconds? echo 'txg_time/D 0t1' | mdb -kw Will change it to every 1s. -- Best regards, Robert mailto:[EMAIL PROTECTED] http://milek.blogspot.com _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
