Recently we launched a new useful tool for the ZFS-based Open-E JovianDSS, available on our website at no cost. Try the storage License Calculator to check the exact license required for your pools and their groups - either data or non-data groups, for your storage setup with Open-E JovianDSS. All you need to select is:
the redundancy level
the number of disks in a group
the number of groups
the size of each disk
The calculator will automatically display the total necessary license capacity. NOTE: Results are shown for single pools only.
Fresh questions regarding performance metrics in calculator at https://www.open-e.com/raid-calculator/joviandss/
- Which assumptions about the load were made to estimate the performance metrics?
- Or, at which load the measured real pool performance will be much close to calculated?
Im suspecting (basing at the metrics grow while increasing number of the disk groups) the metrics are calculated closer to random request distribution. Am I right?
Is the metrics for single disk group as the performance of single drive underestimated? In the classic method, which I know (for Dell Compellent, EMC VNX, and Dell MD storages) the more drives in a disk group, the more performance that group has (in a single or multiple disk groups array). Does Open-E planning to publish revised results?
Answering the first question.
Yes, the performance metrics is calculated on random request distribution.
About the second question.
In ZFS the performance is scaling on a vdev and not on a disk group level.
So, for example the stripe is populated on vdevs, and therefore the best performance can be achieved with the disks used as singles, but there won't be any redundancy of course.
The next performance tier would be to use mirror groups, so we have a redundancy on 1 disk in a group.
More complicated raidz's are giving a better redundancy with the cost of a performance.
Thank You, T-Ku, thus, the performance index reflects scaling by the number of disk groups (vdevs, https://www.freebsd.org/doc/handbook/zfs-term.html). Still the disk group performance remains unclear. The calculator help states "The disks in a data group work in unison, which means that their effective performance is the same as one disk, no matter how many there are", which is very ugly in comparison with traditional approach. May be, after more statistics will be available, the calculator will be much optimistic, closer to "Complex RAID Performance" chapter at https://www.storagecraft.com/blog/raid-performance/