![]() ![]() ![]() Each vdev, in turn, consists of one or more real devices. vdevĮach zpool consists of one or more vdevs(short for virtual device). Such a mismatched pool will still generally perform as though it were entirely composed of the slowest device present. The utilization awareness mechanism built into modern ZFS write distribution methods can decrease latency and increase throughput during periods of unusually high load-but it should not be mistaken for carte blanche to mix slow rust disks and fast SSDs willy-nilly in the same pool. In more recent versions of ZFS, vdev utilization may also be taken into account-if one vdev is significantly busier than another (ex: due to read load), it may be skipped temporarily for write despite having the highest ratio of free space available. A zpool is not a funny-looking RAID0-it's a funny-looking JBOD, with a complex distribution mechanism subject to change.įor the most part, writes are distributed across available vdevs in accordance to their available free space, so that all vdevs will theoretically become full at the same time. It is a common misconception that ZFS "stripes" writes across the pool-but this is inaccurate. Modern zpools can survive the loss of a CACHE or LOG vdev-though they may lose a small amount of dirty data, if they lose a LOG vdev during a power outage or system crash. Just know up front that in the understated words of OpenZFS developer Matt Ahrens, "it's really complicated."īut before we get to the numbers-and they are coming, I promise!-for all the ways you can shape eight disks' worth of ZFS, we need to talk about how ZFS stores your data on-disk in the first place. Well, today is the day to explore, ZFS-curious readers. In the second of those stories, we even promised a follow-up exploring the performance of various multiple-disk topologies in ZFS, the next-gen filesystem you have heard about because of its appearances everywhere from Apple to Ubuntu. Understanding RAID: How performance scales from one disk to eightĪs we all enter month three of the COVID-19 pandemic and look for new projects to keep us engaged ( read: sane), can we interest you in learning the fundamentals of computer storage? Quietly this spring, we've already gone over some necessary basics like how to test the speed of your disks and what the heck RAID is.ZFS 101-Understanding ZFS storage and performance.ZFS versus RAID: Eight Ironwolf disks, two filesystems, one winner.Return to RAID: The Ars readers “What If?” edition.OpenZFS 2.1 is out-let’s talk about its brand-new dRAID vdevs.Jim Salter reader comments 259 with Storage fundamentals ![]()
0 Comments
Leave a Reply. |