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Scrub feature takes too long to use...
Let's talk about the scrub feature. Is anybody actually using it?
I know scrubbing is slow. I expect that. I have the scrub schedule set to do it once every three months. The problem is, it is so slow that I have to abort it so I can use my NAS (and I fear it's destroying the life of the drives). The last time the scrub started, I let it go until it got to a little over 5% complete. That's how far it got after more than two days.
That was with version 6.4.1. I'm now at 6.4.2, so I thought I'd have another look. Nope, still super-slow. My attitude had been, "Well, at least the NAS is working, I can do without the scrub." But I hate that. The NAS has a lot of data that I almost never access (actually most of the data is never accessed). I need to do the scrub so that I'll feel that the data is safe.
So today I started the scrub again, an hour ago. It is now at 1.45%. That is actually better than 5% after two days, but, extrapolating this out, 100% won't be reached until about 70 hours. That's nearly 3 days. And that's assuming it doesn't slow down (or speed up, i suppose).
I kinda remember the first couple of times doing a scrub, it took a long time (again, expected), but it was less than a day. It was measured in hours, not days. This would have been pre-6.4.1. Maybe even pre-6.4. I don't recall.
Can anybody offer insight here? Is 3 days what we should expect? If that's the case, the scheduling system is inadequate. I would need to be able to say something like, "Scrub every three months, starting on a Friday evening," so that it would have the whole weekend, without being needed.
Thanks.
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I run scrubs quarterly. the last one took 66 hours on a volume with 4.5 TB of data on my RN202.
This does take a long time, but it verifies that all the files on the NAS are readable, and that there are no latent issues with bad disk sectors.
As far as I can tell, there is no way to speed it up (and frankly I don't want it skip over files).
I think there are other folks who have wanted to schedule tests on weekends. OS 4.2.x let you do that easily, but OS 6 does not. It'd be helpful if you could schedule by day of week, and not date. (2nd Friday, etc).
Just an update:
I'm now at 2% complete, and it's been going for 4 hours. Extrapolating, that's a total of 200 hours to get to 100%. That's just not doable. 200 hours is more than a full week (8.33 days).
Is there something I can check that may be wrong with my NAS that could cause this? Looking at the output of top, I see three kworker processes, each taking just under 30% CPU. Does this seem right?
Mine started slow, and then picked up speed - so I'm not sure that you can simply extrapolate.
How much data is in the data volume?
Data volume is only at 1.85 TB (of 5.40 TB). I get that the scrub speed is going to vary. It already has changed by quite a bit (unfortunately, in the wrong direction).
I'm going to wait this one out for at least a few days, to see how far it will get. But, like I said, the last time it took two days to get to 5%. Unless the next 95% was going to go 38 times faster than the first 5%, it wasn't going to get finished in 3 days.
I guess this is why I'm posting. I'm trying to find out if my NAS is out of whack, compared to other people that scrub.
I stopped it after more than 10 hours, at 2.84% complete.
Tomorrow I'm doing a factory reset and restore from my backup. Then I'll see if the scrubbing performs better.
The fun never ends. So I'm in the middle of getting the factory reset done. I'm now sitting with a reset NAS, waiting for the resync to finish before I can restore the configuration and the data from the backup (BTW, which of those should I do first?).
So now my question is: is it normal for the resync to take forever? This feels exactly like the slow scrub issue. It's reporting that the resync is going to take 43 hours. No wait, it just jumped to 48 hours. Yikes.
I just started a scub on my RN204 with 2 x 2 TB WD Red with approx. 900 GB of data on it.
The NAS was booted the first time on 9th of January and it is the first time i am running a scrub.
It has been running for 50 minutes and is 4.67% complete.
Hello spotcatbug,
File system check and RAID resync can take a while as they read entire partition and a bit slow. Both slow down more on a weaker processor like the 100 series. 2 days I think is okay but if it feels that it will take longer than that, maybe you need to contact support center.
Regards,
UPDATE
OK, I'm back. Factory reset, restore from backup and resync are complete. Now wouldn't normally be the time to do a scrub, but I'm curious if the reset fixed whatever my issue was. I just started a scrub at 18:23 EST. I'll report back when it's done.
OK, it's exactly 24 hours later (18:23 EST, the next day) and the scrub is at 50% complete. This is still very slow, but more than an order of magnitude faster than it was before I did the factory reset. I'll report back at 100%. If it ends up that the scrub takes 48 hours, I'll be happy. 48 Hours, every 3 months is fine.
Finished at16:39 EST today, 44 hours and 16 minutes, total elapsed scrub time. The factory reset definitely fixed whatever was slowing down the scrubbing.
I will be happy to let a scrub happen over the weekend, every three months, starting on a Friday afternoon. I really wish I could schedule it like that, but I'll just let it try to scrub on the first of the month, every three months and then stop it and remember to start it manually on that week's Friday afternoon.
For others, like me, that are looking for answers and solutions.
ReadyNAS 102 - OS 6.5.1 - Used to store backup.
2 x 6TB WD Red 5700 RPM disks in raid 1.
2TB of data, 0.4 TB snapshots, 3TB empty.
Running the ReadyNAS backup application and using it as FTP server to receive backup files.
Bit Rot Protection is enabled and the Log Analyzer app was running.
Snapshots are turned on, once every 24 hours.
I had run both balancing and defrag some days before. They each took around 2 hours to run.
My experience with scrubbing is as follows:
- Started scrubbing 9:30 on a wednesday morning.
- 24 hours later the scrubbing had reached 5% indicating it would take 20 days!
- After 48 hours it was at 8,5% and an unresponsive/slow web interface. Looked for som answers and found this thread. Turned the Log Analyzer off (installed but off). The web interface became more responsive.
- After 72 hours the scrubbing was at 10,5%. Not looking good.
- After 84 hours the scrubbing had suddenly jumped from10,5% to 52% in 12 hours!
- After 16 more hours the scrubbing finished.
- A total of 100 hours to scrub 2TB of data on 2x6TB disks.
- During these 100 hours the ReadyNAS was slow but responsive over SMB and FTP.
- During this period the ReadyNAS received several hundred GB of data through FTP and its own backup application.
- Around 25 FTP backup jobs and 15 native backup jobs ran during these 100 hours.
- The backup time for these 40 backup jobs was 3 to 10 times slower than before.
- Had to cansel 1 or 2 FTP backup jobs because they stalled and would not continue. Have never had to do that before using the ReadyNAS.
Regards
Johann Hjaltason
FWIW I started a a message intending to provide 'standard' times for Scrubbing, back in 2015, which was still active earlier this year.
The link is https://community.netgear.com/t5/New-to-ReadyNAS/Data-Scrubbing-Find-out-how-long/td-p/936345 and there MAY be some useful stuff in there.
Somewhere else in another message (can't find it now) I suggested a repository of useful info like this, updateable only by 'qualified' people to maintain standards and only provide the facts.
This was thought to be a wonderful idea, by everyone, but does not seem to have been taken onboard by anyone (please contradict me if this has been done).
My objective in doing all this was to help new and existing users with their expectations of the equipment they have bought.
( I also did messages on the other 3 scheduleable activities, in a simialr vein to the scrub one mention above).
I feel like a hermit as my faith has been dented when my seed fell on stoney ground AND did not germinate owing to lack of watering.
My RN516 with OS 6.5.1 is setup as 6 discs of 4TB (WD Reds) in RAID10 and is lightly used.
Data --------- 1.12 TB
Snapshots - 0.73 TB
Free --------- 9.06 TB
Total ------- 10.90 TB
The last run for Data Scrubbing was 21hrs 23 mins, although previous runs have varied from initially 17hrs 34mins through to 19hrs 05mins.
I now run them every 3 months, having run 7 since begining of 2015.
Hope this was helpful.
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