write speed fluctuate

[agrabn]

Hi

My question is does anyone know why write speed drop drop 250Mb/s to 20-30Mb for minute or more and go beck to 200-250Mb/s for a minute or 2 make next circle.

System:
4x red 4TB
6700K i7
2,5Gb network card
40gb ram
128 nvme for boot

add1: ipfer run 2,5Gb, cable go from nas to my pc, no route
add2: it does the same with 1G network card after few minutes write speed go to 20Mb/s

Thanks

 

[HoneyBadger]

Hey @agrabn

What are the exact model of your WD Red drives? Certain lines used Shingled Media Recording which does not work well with TrueNAS and ZFS.

 

[agrabn]

WDC_WD40EFAX-68JH4N0

 

[NugentS]

EFAX - Oh Dear
These are SMR drives and belong in landfill (IMHO). You should look at replacing these as soon as convenient with a certain degree of urgency. These drives are the cause of pools failing with ZFS

 

[Redcoat]

WDC_WD40EFAX-68JH4N0

Well, @HoneyBadger hit the nail on the head - that's an SMR drive model number.

Lifting text from a forum post by @Arwen:
https://www.truenas.com/community/threads/10g-network-upgrade-next-steps.108883/#post-751996

" SMR drives are both slower for write and because of the fragmentation possible, reading can be slower than expected. Further, drive replacement with SMR drives is much slower. The upshot is that SMR drives are not recommended for use with ZFS.

Suggested reading about SMR drives:

List of known SMR drives​

Hard drives that write data in overlapping, "shingled" tracks, have greater areal density than ones that do not. For cost and capacity reasons, manufacturers are increasingly moving to SMR, Shingled Magnetic Recording. SMR is a form of PMR...
www.truenas.com

Update: WD Red SMR Drive Compatibility with ZFS​

Thanks to the FreeNAS community, we uncovered and reported on a ZFS compatibility issue with some capacities (6TB and under) of WD Red drives that use SMR (Shingled Magnetic Recording) technology. Most HDDs use CMR (Conventional Magnetic Recording) technology which works well with ZFS. Below is...
www.truenas.com

WD Red SMR Drive Compatibility with ZFS​

Thanks to the FreeNAS community, we have uncovered a potential ZFS compatibility issue with some capacities of newer WD Red drives that use SMR (Shingled Magnetic Recording) technology. Update to this post...
www.truenas.com"

@Arwen has written many posts including information and advice about the use/non-use of SMR drives - search here for SMR with author Arwen to see them.

 

[agrabn]

Thanks. Now I know why.
Do I will be replacing red disk. Thanks for list of not recommended disks. Can anyone recommend 4 tb good disks? Thanks for that.
and F*** WD RED, for misleading naming convention of WD product.

I feel stupid right now.

 

[HoneyBadger]

WD Red Plus is the CMR drive lineup; there's also the Seagate Ironwolf line that's fairly popular. Don't recall the Toshiba one off the top, and don't want to accidentally suggest another SMR model accidentally - just ensure you avoid that technology.

 

[NugentS]

You might be able to return them to WD as not fit for purpose, depending on when you got them

WD Red Plus are good, Any Enterprise Drive are all good. Any NAS drive (except for WD Red)

 

[Davvo]

WD usually swaps them for CMR ones if you contact their customer service I believe.