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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 understand the risks of asynchronous data transfers and the need for a UPS.
Thanks for letting know where the NFSv4 option was. It wouldn't have come to mind to check there. Just out of curiosity, is there a reason it is not default on?
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 wouldn't judge performance based on what you get during a resync.
Have you had a look at top output etc. ?
Presumably some don't use NFSv4 and leaving that disabled may help with some such use cases.
mdgm wrote:
I wouldn't judge performance based on what you get during a resync.
As said before, I didnt just judge it during resync. I focused on the results after resync. I included the 'during resync' just so one could have some feel of what kind of impact it would happen.
My final tests where all based on after resync was completed. If that was unclear, I shall rephrase my last post to be more clear on that
mdgm wrote:Have you had a look at top output etc. ?
Yes I have, and had replied to it.
My conclusion was that (after resync) the speed are comparable to that, albeit slightly lower. A sustained transfer-speed of 120mb/sec with real-life data (rsync over NFS (non v4) with async turned on).
An interesting sidenote is that the performance degradation due to a full volume (> 75%, and even > 95%) was noticably less than on OS4 versions. Even at > 95% the speeds still remain around the 120 mb/sec, which is a pleasant surprise.
All-in-all I'm quite satisfied with the result. The (slightly) less performance in exchange for a more reliable filesystem and reliable speeds at higer volume usage is a (very) small price to pay.
Still you are best not to fill it over 95%. Keeping volume usage down to 80-85% or lower is best.
Thanks for the reminder, I was also aware of this. The reason this is (temporarily) done is so the backup disks (its raid set in which they were used to backup the NAS to) can be used for non-critical information which was previously stored on the NAS. This data (which is now stored on the NAS) will be removed from the NAS, and transfered to these disks for cold-storage.
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