[SOLVED] Calculate IOPS from MBPS ?

[srmvel]

Hi Team,



I'm going to setup three storage Ceph server with cluster.

Each server has 9300-8i controller with 8*2tb sata ssd disks.



Overall throughout of 8 drives and per drive throughout is mentioned below.



So 4480 MB/s / 8 SSD = 560 MB/s per drive.



There is no hardware raid concept here and all will be taken care by Ceph.



From just one server calculation.



IOPS = (MBps Throughput/KB per IO) * 1024



Iops = 560/4 *1024 = 143,360



560 -- Per drive throughput

4 kb ----- block size



So 1,003,520 iops from all the 8 drives?

Is this correct calc?

 

[velocityg4]

IOPS isn’t straight throughput. It would be how many 4KB files it can transfer per second. Which is a lot different than straight throughput. As there is latency between each I/O command.

Then you also have to factor in Queue Depth (QD). SSD generally do better if there is a high Queue Depth (QD1 to QD 1-128). High quality SSD do much better. As they are able to efficiently organize pending commands to optimize throughput. As this is a server. Queue depth is important. Since it'll be seeing multiple IO requests at a time.

https://www.tomshardware.com/reviews/ssd-gaming-performance,2991-3.html

I'd just use what Tomshardware uses in their reviews to measure IOPS. (IOMETER)
https://www.tomshardware.com/reviews/sabrent-rocket-4-plus-m2-nvme-ssd-review/2

Now with SATA SSD. You'll be lucky to hit 9,000 IOPS with a QD1 and 60,000 with a Q1-128 when reading. Having RAID 0 and a very nice RAID controller may help that some. But it won't be a linear progression in RAID. If IOPS is important. You should be using NVMe SSD. As you may get 18,000 IOPS with a QD1 and 600,000 IOPS QD 1-128 when reading. I'm just focusing on read. There's also writes to consider too but a good NVMe will still do way better than SATA.

High end SATA SSD IOPS: https://www.tomshardware.com/reviews/samsung-870-evo-sata-ssd-review-the-best-just-got-better/2
High End NVMe IOPS: https://www.tomshardware.com/reviews/sabrent-rocket-4-plus-m2-nvme-ssd-review/2

With NVMe. You could go with a x16 PCIe card. One which will allow for four NVMe SSD. Then go with 4x4TB M.2 NVMe. Getting the same amount of storage but much higher IOPS. Assuming your motherboard can handle it. As sometimes those cards don't play nice with all motherboards.

If this is some mixed environment. Where you have some database which needs high IOPS but not a lot of storage. You could use one NVMe for that. Then the SATA for regular files. Such as word documents, powerpoint, &c. As IOPS won't matter nearly so much for files over 512KB.

 

[srmvel]

Thanks much for your inputs.