3 ms·
Slightly off topic, but can someone explain what happens when you use multiple vdevs in the same zfs pool as shown in their diagram? Does any data in the zpool
by aquova 4y ago
Slightly off topic, but can someone explain what happens when you use multiple vdevs in the same zfs pool as shown in their diagram? Does any data in the zpool get written to both vdev1 and vdev2 in its entirety, part to each, or entirely to one or the other? It always seemed to me that it would be better to have two zpools with one vdev each rather than one zpool with two vdevs, but maybe there's something I don't understand.
- yabones 4y agoMultiple VDEVs in one pool = striping. To build a traditional RAID10 on ZFS, you'd create several mirror vdev's, then add them to the same pool. This writes one strip to vdev1, the next to vdev2, etc. Should also be noted that it doesn't rebalance, so adding a vdev to a pool won't re-distribute data throughout the pool; new data will concentrate on the new vdev and potentially degrade performance until they're roughly at the same fill level. (edit) Real world example: this is a NAS that has 3 pairs of mirrors. Writes are a little faster than a single disk since it can hit three at a time. Data correction is possible because every chunk of data has a mirror. And, since it's three mirrors I could potentially lose 1 disk in any vdev at the same time without data loss. % zpool status NAME STATE READ WRITE CKSUM data ONLINE 0 0 0 mirror-0 ONLINE 0 0 0 ada0 ONLINE 0 0 0 ada2 ONLINE 0 0 0 mirror-1 ONLINE 0 0 0 ada3 ONLINE 0 0 0 da0 ONLINE 0 0 0 mirror-2 ONLINE 0 0 0 da1 ONLINE 0 0 0 da2 ONLINE 0 0 0
- radiowave 4y agoAFAICT, the diagram is just there is illustrate the differences between the types of vdev. It doesn't represent a sensible configuration, nor is it what the rest of the article is talking about actually doing.