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I/O Performance
TheBrokenBee
Member
Recently picked up a storage server. I am not really sure if the IO speeds here are upto par but what exactly are implications of different write speeds of 4K/64K/512K/1M in terms of system performance? Is it better to have better 4k speeds or 1m speeds?
fio Disk Speed Tests (Mixed R/W 50/50):
---------------------------------
Block Size | 4k (IOPS) | 64k (IOPS)
------ | --- ---- | ---- ----
Read | 33.68 MB/s (8.4k) | 206.21 MB/s (3.2k)
Write | 33.76 MB/s (8.4k) | 207.30 MB/s (3.2k)
Total | 67.45 MB/s (16.8k) | 413.51 MB/s (6.4k)
| |
Block Size | 512k (IOPS) | 1m (IOPS)
------ | --- ---- | ---- ----
Read | 211.69 MB/s (413) | 209.83 MB/s (204)
Write | 222.94 MB/s (435) | 223.81 MB/s (218)
Total | 434.64 MB/s (848) | 433.65 MB/s (422)
Comments
Depends on your use case. Roughly: great 4k values mean better overall responsiveness whenever disk is under heavy load (lots of r/w operations, smokin'hot database, metadata update etc.). If huge speeds when reading/writing (big) files matter to you (e.g. to upload or download lotz of ISOz very very fast), other values are important too.
Are these values in the original post good for a HDD?
yes, they are pretty decent i'd say
4K speeds are always going to be slower than 1M speeds as this is (I assume) random access. For traditional drives this will mean much more time spent moving the heads around, and for SSDs there will still be a difference but a much less pronounced one.
Which benchmark is more meaningful to you, if either, depends massively on what you'll be using the server for.
IF those numbers reflect real disk performance they are quite good. Do not expect those numbers with your applications though.
Those are numbers are good for HDD, yes.
agreed, from the numbers that's either SSD or well cached HDD raid/zfs etc.
He specifically asked for HDD! so yes they are good for HDD?
They're way too good for HDD. Its SSD/RAM cached.
In fact your 4k speeds are 4x better than "SSD" plan in Contabo.
Storage plan with that kind of performance? Amazing!
4k is important for random small data - example: databases.
1M is important for big files - example: streaming videos.
Or, shorter: A disk with good 4K speed (and decent IOPS) will virtually always also be decent at larger block sizes.
How do folks feel about this as a SSD when the above was a HDD? Why is the 4K so much slower or is that normal?
the 4k is iops limited.
This test DOESNT REFLECT HDD. We already replied to it. Its impossible to get such HIGH 4K speeds. average HDD has just 1MB/s in 4K. This test is on RAM/SSD Cache of this server, because no HDD can reach these speeds.
this.
as @skorupion wrote the new bench does look like IO is limited - which from a providers makes sense to balnce systems more easily. this might be preferable from a user point of view as well if the limit is a reasonable one and keeps otherwise noisy neighbours at bay.
in comparison the numbers from the initial bench won't represent raw HDD perfomance as that's simply crossing technical limitations. instead what you have there is in some way cached as already pointed out.
as always: take every benchmark with a grain of salt. it's usually just a narrow and specific scenario that leaves a lot of room for misinterpretation. does not mean any of those two thingies is bad at all.
First: Be very mistrusting when read and write speeds are basically the same, because in reality they are not by any means.
Now, if I forgot everything I know about disks and about benchmarking them that is if I just looked at the write speed results and bluntly trusted them, I'd say that that disk is highly likely an SSD and one with about typical performance.
But I don't. I prefer to think that those results may show anything from a heavily cached HDD up to a (not exactly great) NVMe or, btw, a network attached (cached, of course) drive but probably is about a SSD.
Although, frankly, based on those numbers I'd prefer to limit my comment to a polite "Uhum. Interesting".