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Forum Discussion
terrible write performance when almost full
Hi, I own a NV+ V2, and have been loving it so far. My issue has happened recently when the device is almost full. Basically, I can not write the last 70 GB free on the device. I have 4x spinpoint 2GB drives, all the same model and on the compat list. I have them all setup as a single pool in X-RAID2. I still read off the device at 60+ MB/s under both windows and OSX, but when I try to write, small files work, but usually at around 200k/s and all large files just fail. this happens under windows and osx, and also FTP. Basically I just get timeouts.
The only add-in I have is SSH, and while running TOP, the cpu's are not busy. Samba is also not working most of the time.
Anything to check? All the logs and drive temps etc seem to be fine. I am also running 5.3.5, but this problem was also happening under 5.3.4 before I upgraded.
Thanks!
The only add-in I have is SSH, and while running TOP, the cpu's are not busy. Samba is also not working most of the time.
Anything to check? All the logs and drive temps etc seem to be fine. I am also running 5.3.5, but this problem was also happening under 5.3.4 before I upgraded.
Thanks!
27 Replies
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- Hi buchhla,
Sorry! this is know issue, the performance become low when Data volume almost full, we are checking the root cause.
Thanks for your report. - Thanks, are there any work arounds for this? I would really love to be able to use the last 100GB or so of my volume!
- I thought it was just me. I upgraded to 4.1.19 (Sparc) and saw the speed increase straight away to 35 -45 Mb/s. Then a week later with 100Gb left on the 3 x 2Tb drives it dropped to the 5-6Mb/s.
I have ordered another set of 2Gb drives for the two NV+ systems, it should not be a problem after this week. BUT I would hardly describe 70, 90 or 100Gb as being a small amount of data, why is there an issue writing to this last chunk which in my case is about 2% of the overall capacity?
Strange indeed. Do the problems ever end? - Just a guess, but I'd think that the last 2% of the volume would be very fragmented. The extra seeks would account for the terrible write performance.
- This entire NAS was basically filled up all at the same time, so there is little fragmentation. And I would love to get something in the MB/s area, If copies don't timeout completly, explorer or the finder depending on OS usually show transfer rates in the single KB/s, so I think it is something more than just fragmentation.
Maybe you can try comparing read speeds on the older files with read speeds on the new files. If it is related to fragmentation, then the old files will still be read at the original speeds.buchhla wrote: This entire NAS was basically filled up all at the same time, so there is little fragmentation. And I would love to get something in the MB/s area, If copies don't timeout completly, explorer or the finder depending on OS usually show transfer rates in the single KB/s, so I think it is something more than just fragmentation.
Not sure why you are determined to completely fill the file system though. The normal rule of thumb I've seen is that ext3 performance drops rapidly when the volume exceeds 95% full.- Yea, I am aware of all of that, but since this unit basically just stores music and movies for me, I am not worried about the hit at the end, and I would like to use all the available space. I have had three other Linux NAS's before this, one QNAP and two Synology and I have had this problem with either. I am wondering if there might be something with X-RAID that is causing this because that is really the only difference between this device and the others I have used in the past...
I did check, read speeds are pretty uniform between older files and newer files, but most of the newer files are small, since anything over 10MBs or so times out, and this is via CIFS, NFS, and FTP, so it is something low level that is causing the issue I think... - Does reboot help to fix this ?
- Nope, reboot does the same thing. Sadly, the only way to really play with this phenomenon is to back up the entire unit and see how/if it reproduces when near full, but since I am in a remote bay in Fiji without access to that kind of storage, it will have to wait for now...
- I'd guess it boils down to fragmentation, like Stephen said. EXT3 is supposedly a intelligent file system, and leaves small gaps of empty space, to leave space for files to grow when changed, such as editing. There really should be a way to defrag the units, regardless of if NetGEAR thinks the performance loss is minimal. But, there isn't.
B!
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