> You do not need to mirror the L2ARC devices, as the > system will just hit disk as necessary. Mirroring > sounds like a good idea on the SLOG, but this has > been much discussed on the forums.
Ah, ok. > Interesting. I find IOPS is more proportional to the > number of VMs vs disk space. > > User: I need a VM that will consume up to 80G in two > years, so give me an 80G disk. > Me: OK, but recall we can expand disks and > filesystems on the fly, without downtime. > User: Well, that is cool, but 80G to start with > please. > Me: <sigh> One of the reasons I am investigating solaris for this is sparse volumes and dedupe could really help here. Currently we use direct attached storage on the dom0s and allocate an LVM to the domU on creation. Just like your example above, we have lots of those "80G to start with please" volumes with 10's of GB unused. I also think this data set would dedupe quite well since there are a great many identical OS files across the domUs. Is that assumption correct? > I also believe the SLOG and L2ARC will make using > high RPM disks not as necessary. But, from what I > have read, higher RPM disks will greatly help with > scrubs and reslivers. Maybe two pools - one with fast > mirrored SAS, another with big SATA. Or all SATA, but > one pool with mirrors, another with raidz2. Many > options. But measure to see what works for you. > iometer is great for that, I find. Yes. As part of testing this I had planned to look at the performance of the config and try some other options too, such as using a volume of 2 x mirrors. Its a classic case of balancing performance, cost and redundancy/time to resilver. > One of the benefits of a SLOG on the SAS/SATA bus is > for a cluster. If one node goes down, the other can > bring up the pool, check the ZIL for any necessary > transactions, and apply them. To do this with battery > backed cache, you would need fancy interconnects > between the nodes, cache mirroring, etc. All of those > things that SAN array products do. I've not seen an example of that before. Do you mean having two 'head units' connected to an external JBOD enclosure or a proper HA cluster type configuration where the entire thing, disks and all, are duplicated? Matt. -- This message posted from opensolaris.org _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
