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Forum Discussion
ReadyNAS 4200 poor write performance
Hi All, We've had a Readynas 4200 in service for a while as a backup of retired computer images The NAS connects to a 2019 server using iSCSI on a single gigabit NIC No errors showing on the NAS i...
gleach wrote:
Write performance on the unit however is terrible, starting around 150MB / sec sustained copy then tanking after a couple gig copied to 10 - 20MB / sec, write have previously been similar speeds to reads
Sounds like you might have some SMR disks installed. What disks are you using (manufacturer/model)?
Have you done anything to check the disk health?
Hi StephenB,
We're using Hitachi disks in the NAS, it's been running for a few years (probably close to 3 years) without any write performance issues, hence asking here to try and figure out what's going on with it
Drive model of most of the drives is HUA722020ALA330 with a couple of HUA723020ALA640 as well, from what I know of the history of the unit, the 330 drives are what came with it when it was purchased, they're only 2tb drives so not sure if there even would be smr drives of that capacity and age, I've checked and they are listed as enterprise drives so unlikely to be smr
I've checked the smart status of all the drives and 2 or 3 have a couple of reallocated sectors but nothing growing, no failed drives or anything like that
I've tested write performance from the server that the NAS is connected to via iSCSI and the write performance is still poor
gleach wrote:
Drive model of most of the drives is HUA722020ALA330 with a couple of HUA723020ALA640 as well, from what I know of the history of the unit, the 330 drives are what came with it when it was purchased, they're only 2tb drives so not sure if there even would be smr drives of that capacity and age, I've checked and they are listed as enterprise drives so unlikely to be smr
The drives were launched 10-13 years ago. No idea when WD stopped making them (they phased out the Hitachi brand in 2015).
These would be CMR. I don't know of any enterprise class SMR drives. Most desktop drives between 2 and 6 TB are now SMR. WD Reds are as well (though WD Red Plus and Red Pro are CMR).
Do you only use iSCSI, or is it also accessed with other protocols? Is the LUN provisioned as thick? or thin?
Do you have snapshots enabled for the LUN?
Hi Stephen,
to be honest i'm not sure if the LUN is thin or thick provision as there isn't an option for thick / thin provision when we create an iSCSI target or volume, we can only specify the LUN number, name and size
Snapshots aren't enabled on the box at all, nor are any of the volume maintenance / scrubbing options
The box is only accessed via iSCSI from the host it's connected to, all other procotols are off
gleach wrote:to be honest i'm not sure if the LUN is thin or thick provision as there isn't an option for thick / thin provision when we create an iSCSI target or volume, we can only specify the LUN number, name and size
Actually you can tell if the LUN is created on the NAS. One way is that the icon is different - see page 95 here:
You can also see this and other properties by looking at the LUN settings - see pages 99-100. Make sure that snapshots aren't enabled for the LUN (looking at the snapshot page for the LUN settings).
Possibilities I can think of off-hand that might affect write performance are
- the LUN storage container itself has become fragmented (which could be the case if it is thin, or if snapshots are/were enabled for it).
- compression is enabled for the LUN storage container
- sync writes is set to forced (or perhaps even allowed might hurt performance).
- the file system on the LUN has gotten fragmented
- One or more of the disks in the array are misbehaving.
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