On Tue, June 15, 2010 14:13, CarlPalmer wrote: > I have been researching different types of raids, and I happened across > raidz, and I am blown away. I have been trying to find resources to > answer some of my questions, but many of them are either over my head in > terms of details, or foreign to me as I am a linux noob, and I have to > admit I have never even looked at Solaris.
Heh; caught another one :-) . > Are the Parity drives just that, a drive assigned to parity, or is the > parity shared over several drives? No drives are formally designated for "parity"; all n drives in the RAIDZ vdev are used together in such a way that you can lose one drive without loss of data, but exactly which bits are "data" and which bits are "parity" and where they are stored is not something the admin has to think about or know (and in fact cannot know). > I understand that you can build a raidz2 that will have 2 parity disks. > So in theory I could lose 2 disks and still rebuild my array so long as > they are not both the parity disks correct? Any two disks out of a raidz2 vdev can be lost. Lose a third before the recover completes and your data is toast. > I understand that you can have Spares assigned to the raid, so that if a > drive fails, it will immediately grab the spare and rebuild the damaged > drive. Is this correct? Yes, RAIDZ (including z2 and z3) and mirror vdevs will grab a "hot spare" if one is assigned and needed, and start the resilvering operation immediately. > Now I can not find anything on how much space is taken up in the raidz1 or > raidz2. If all the drives are the same size, does a raidz2 take up the > space of 2 of the drives for parity, or is the space calculation > different? That's the right calculation. > I get that you can not expand a raidz as you would a normal raid, by > simply slapping on a drive. Instead it seems that the preferred method is > to create a new raidz. Now Lets say that I want to add another raidz1 to > my system, can I get the OS to present this as one big drive with the > space from both raid pools? You can't expand a normal RAID, either, anywhere I've ever seen. A "pool" can contain multiple "vdevs". You can add additional vdevs to a pool and the new space become immediately available to the pool, and hence to anything (like a filesystem) drawing from that pool. (The zpool command will attempt to stop you from mixing vdevs of different redundancy in the same pool, but you can force it to let you. Mixing a RAIDZ vdev and a RAIDZ3 vdev in the same pool is a silly thing to do, since you don't control where in the pool any new data goes, and it's likely to be striped across the vdevs in the pool.) You can also replace all the drives in a vdev, serially (and waiting for the resilver to complete at each step before continuing to the next drive), and if the new drives are larger than the old drives, when you've replaced all of them the new space will be usable in that vdev. This is particularly useful with mirrors, where there are only two drives to replace. (Well, actually, ZFS mirrors can have any number of drives. To avoid the risk of loss when upgrading the drives in a mirror, attach the new bigger drive FIRST, wait for the resilver, and THEN detach one of the smaller original drives, repeat for the second drive, and you will never go to a redundancy lower than 2. You can even attach BOTH new disks at once, if you have the slots and controller space, and have a 4-way mirror for a while. Somebody reported configuring ALL the drives in a 'Thumper' as a mirror, a 48-way mirror, just to see if it worked. It did.) > How do I share these types of raid pools across the network. Or more > specifically, how do I access them from Windows based systems? Is there > any special trick? Nothing special. In-kernel CIFS is better than SAMBA, and supports full NTFS ACLs. I hear it also attaches to AD cleanly, but I haven't done that, don't run AD at home. -- David Dyer-Bennet, d...@dd-b.net; http://dd-b.net/ Snapshots: http://dd-b.net/dd-b/SnapshotAlbum/data/ Photos: http://dd-b.net/photography/gallery/ Dragaera: http://dragaera.info _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
