RN 104 Free space warnings and (suuurprise) slow iSCSI

Question

Hello everybody, it's me again.again and again I'm coming here with useless and slow RND boxes.now I have RN-104 box with latest firmware 6.7.5 with disabled all services except http.there is 4*2Tb WD NASware at X-raid 5.one lun=5Tb and 500+Gb is free.MPIO with RRWS.copy from server to NAS - 22MB\sec.copy from NAS to server - 3MB\sec.&nbsp;and I do have Gbe links there ;)&nbsp;and funny warning at logs:"Volume: Less than 10% of volume data's capacity is free. Performance on volume data is degraded. To improve performance, you must add capacity."&nbsp;550Gb is not enogh? for what????&nbsp;I'm crying every time looking at RN perfomance... why do you have such buggy,ugly,unstable OS with average HW?....&nbsp;&nbsp;&nbsp;&nbsp;

StephenB · Answer

BTRFS uses free space for metadata and snapshots, not just for new files. &nbsp;So it generally does need more free space than ext. &nbsp;Your case is a bit unusual, since you are using iSCSI only.
&nbsp;

What speed do you get with a normal share? &nbsp;
Do you have checksums enabled in the volume settings?

&nbsp;
WingDog wrote:
\...with average HW?....
&nbsp;

Well, you did buy the entry-level ReadyNAS. &nbsp;Now the RN214 is the base model, with a faster CPU and much more memory than your RN104.

WingDog · Answer

&nbsp;StephenB wrote:BTRFS uses free space for metadata and snapshots, not just for new files. &nbsp;So it generally does need more free space than ext. &nbsp;Your case is a bit unusual, since you are using iSCSI only.&nbsp;What speed do you get with a normal share? &nbsp;Do you have checksums enabled in the volume settings?&nbsp;WingDog wrote:\...with average HW?....&nbsp;Well, you did buy the entry-level ReadyNAS. &nbsp;Now the RN214 is the base model, with a faster CPU and much more memory than your RN104.Hi Stephen.I don't need snapshots. totally. no any snapshot.My case is not unusual, cause SMB is much worse in RN, so iSCSI is a solution. Else I may need full-disk encryption or teaming (hense NTRG can't archive SMB3 and other multipath). so this is usual case cause NTRG has one OS for all current NAS.&nbsp;&nbsp;with nornal share I get 35-40MB/sec&nbsp;no, checksums are not enabled.&nbsp;doesn't matter when I did buy it. unworkable devices for YEARS (did you remembe me and 4220 with all level supports around it?) - this does matter.&nbsp;

StephenB · Answer

WingDog wrote:
&nbsp;
I don't need snapshots. totally. no any snapshot.
&nbsp;

Yes I understand that - just saying that the volume warnings need to cover the broader cases (where shares and snapshots are used).
&nbsp;
WingDog wrote:
&nbsp;
My case is not unusual

I don't see many posts from RN100 users who are using iSCSI. &nbsp;So it is a bit unusual (supported, but unusual).
&nbsp;
WingDog wrote:
&nbsp;with normal share I get 35-40MB/sec
&nbsp;

I think that's a usual write speed with an RN100 series. &nbsp;If that's the read-speed, then it sounds a bit slow. &nbsp;Smallnetbuilder tested iSCSI speeds at 40-50 MB/sec (a while ago).
&nbsp;
Is the iSCSI LUN is encypted? &nbsp;If so, did you try a test with a small LUN that is not encypted?

WingDog · Answer

StephenB wrote:WingDog wrote:&nbsp;I don't need snapshots. totally. no any snapshot.&nbsp;Yes I understand that - just saying that the volume warnings need to cover the broader cases (where shares and snapshots are used).&nbsp;WingDog wrote:&nbsp;My case is not unusualI don't see many posts from RN100 users who are using iSCSI. &nbsp;So it is a bit unusual (supported, but unusual).&nbsp;WingDog wrote:&nbsp;with normal share I get 35-40MB/sec&nbsp;I think that's a usual write speed with an RN100 series. &nbsp;If that's the read-speed, then it sounds a bit slow. &nbsp;Smallnetbuilder tested iSCSI speeds at 40-50 MB/sec (a while ago).&nbsp;Is the iSCSI LUN is encypted? &nbsp;If so, did you try a test with a small LUN that is not encypted?&nbsp;Well, ok.if this is normal to have at least a half of one NIC throughput (and less than one HDD speed) why this behavior doesn't covered by manual and tech specs?If vendor (NTGR in this case) has knowledge about poor perfomance why it's Hidden Knowledge?even in 2015 40-50MB/sec it's poor. and 104 is not older.Why there is two NICs? for what? for FO? and 4 HDD? the Box can't serve it.&nbsp;I have Synology DS115j - the same CPU and less RAM.two HDD, one nic.95MB/sec SMB copy speed.80-90 MB/sec iSCSI copy speed.&nbsp;&nbsp;

fluffybunnyuk · Answer

As far back as i can remember (30+years) its always been recommended to leave 15% free because of the slow transfer rates at the backend of the drive. If your first free write block is in the last 15% the performance is terrible due to long stroking between the file and the partition table at the front. Benchies of drives typically show a small drop off at 50% then a big drop off at 70% and by 90% well thats head thrashing territory. Remember you also have to read the linux fs at the front end of the disk too.As to RN104 speed its cpu limited, i tried with 4 ssd cards and it came out with 70mb/sec. Perfectly reasonable i think. I also have an 8 way HARDWARE raid 6 card and with ssd cards attached puts out a sick amount of data /second. So it horses for courses. If you want better speed buy a micro atx system dump lots of ram on it, attach hard drives, boot *nix and raid them. Its definately cheaper than hardware raid but nowhere near as good.

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RN 104 Free space warnings and (suuurprise) slow iSCSI

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