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Pro Pioneer - Poor performance X-RAID Raid-6 with 6x WD Red 3TB
For a really long time I thought the poor performance was due to the fact that I was running an old firmware and had never done a factory reset since 2009 (it was recommended in the past on the forum...
For future readers;
The performance impact boiled down to the following things:
- The RAID implementation currently works different in comparison to older versions of the NAS which has impact on performance, but delivers more reliability
- The implementation of NFS (and/or NFSv4) works different and by default works in a more reliable way. Using the "async" option will greatly improve the speed of transfers, but will greatly increase the risk of faulty transfers in case of power-failure and such
- Performance is (obviously) impacted when there are operations running (ie: (initial) (re)syncing of volumes, balancing, scrubbing, defragmentation, simultanious transfers, etc.)
I tested diskspeeds within my system to evaluate the performance impact. My conclusion for now is that in a RAID-5 or RAID-6 setup the set won't perform better than an individual disk (which was the case in older versions of ReadyNAS but seems to not be true anymore, probably due to the first point). When using the async option, the performance is equal to the individual disks. Note; I have *not* compared speeds using CIFS/Samba. I have tested one time and it seemed that the speeds were comparable to NFS with the async option turned on.
I don't think resync speed is very good measure of performance. Perhaps try Nastester ( http://www.808.dk/?code-csharp-nas-performance )
FWIW, parity blocks are evenly distributed across all the disks.
BTW how much memory do you have? The new systems all have quite a bit more than the stock amount in the legacy x86 NAS.
Probably didnt came across right in the opening post, I explicitly waited untill resyncing was complete and then did write tests to the NAS (primarily because I didnt know if OS6 would handle things differently what might cause slower speeds).
So it is not measured only during the resync (but the numbers seemed to be the same)
I have measured both using real-life data (rsync using random files, and using large (uncompresable) files) both over CIFS (samba) and NFS. As well as synthetic tests using dd on the nas itself (writing /dev/zero to a file, forcing syncs during each write).
Rsync over NFS:
7364 files to consider datafile.dat 2048163840 8% 35.64MB/s 0:09:59
synthetic dd output:
root@NAS:~# dd if=/dev/zero of=/root/testfile bs=10M count=100 oflag=sync 100+0 records in 100+0 records out 1048576000 bytes (1.0 GB) copied, 17.1221 s, 61.2 MB/s
It got 2 units of, I thought 1GB being 2GB in total. However htop says it's only 1GB total, so I guess its 2 dimms of 512MB. Free dictates it has about 450mb used / 200mb cached / 350mb free:
total used free shared buffers cached Mem: 1012920 653800 359120 0 1468 225988 -/+ buffers/cache: 426344 586576 Swap: 2094844 0 2094844
Edit: as it seems, the unit has 2x 1GB but sees only 1 dimm of 1GB. Maybe, I didnt place it back correclty when I cleaned the NAS
Edit2: indeed my 2nd dimm wasn't fitted correctly, it now displays correctly that it has 2GB in totall
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