Recommendation as % of volume used increases
I have a raid 10 consisting originally of 6 x 4tb drives. I recently had a drive fail and in anticipation of needing more storage space I replaced that drive with an 8TB drive.
The raid 10 gives me 12 TB capacity, and the storage used has grown now to 9 TB - more than 50% of the capacity, which presumably will be starting to affect performance.
I’ve considered various options which have pros and cons. One consideration is that it might be useful to plan for future expansion. Rather than the have the expense of buying a whole new set of drives, I’m wondering whether I should upgrade in stages such as:
1) add 2 more 8 tb drives and make an 8 drive raid 10 (using 4tb on each drive) - presumably larger no. of drives will be faster, but having some 8tb drives will be a step towards a future 6 drive raid 10 using 8tb per drive.
2) gradually replace the 4tb drives with 8tb drives, so that eventually all drives are using less than 50% of their capacity (so even if I get towards the full 12tb capacity I’m not going to see a performance impact).
With option 2, would I fail to see any performance gain until all drives have been replaced with 8tb drives, or would there be an incremental gain?
From what I’ve read it’s better to backup all the data and make a new raid than to resize the volume, but is there any downside to option 2 (ie not changing the volume size) and replacing 1 drive at a time? (I do have various backups anyway).
You will get modest incremental gains as you replace drives, yes. Modest, though.
There is no real downside to 2, it just takes more time. One benefit of backup/restore is defragmenting the volume.
Thanks for the reply. If I have the 6 drive raid 10 using 4tb drives, and replace 3 of the drives with 8tb drives, should I make the 8tb drives the Primary drives - is that possible and if so would it improve performance? (Presumably modest as you say).
Would adding 2 8tb drives to make it an 8 drive raid 10 benefit performance in terms of defrag, each drive having lower proportion used, and speed improvements of 8 drives vs 6? (Doing backup and restore). Which of these would make the biggest difference?
Once a volume has been "validated" you can make any disk a primary without worrying about it.
So yes you could. But there are other ways to increase performance. RAID 10 is not the best performer, it is targeting environments where robustness is the most important factor. RAID 5 gives much better performance if that is your objective. (And in both cases, you still need a backup strategy!)
How about another idea?
Get 3 large SSD's. Use them as the primary disks. That will greatly improve performance. that may be a better path. 4TB SSD's are still pretty expensive, so you probably have to wait, but keep it in mind.
And we will be implementing another feature soon to build on that performance increase.
Strangely I cannot see any of the drives in my raid 10 marked as primary or secondary. I thought I had previously, but currently cannot see anything that tells me, even when I expand the information for each drive. What am I missing?
Actually - ignore me. When I select the volume, the drives are then shown as primary or secondary.