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Forum Discussion
Data Scrubbing - Find out how long?
Being new to ReadyNAS there were various things I wanted to know.
One of these was Data Scrubbing.
Now having understood more about it, the obvious question is how long does it take.
I have now done two data scrubs and intend to do them every 3 or 4 months (gleaned from other posts).
The data below MAY be useful to new persons similar to myself and help people with their expectations.
So I suggest that those who are interested post their information as follows here, in the format below.
System ..... OS ....... RAID .... Disks ......... Total ........ Scrubbing time
RN516 ...... 6.2.2 .... 10 ....... 6 of 4 TB .... 10.90 TiB ... 17 Hrs 35 Mins - Identical time on 2 runs.
RN516 ...... 6.2.3 .... 10 ....... 6 of 4 TB .... 10.90 TiB ... 17 Hrs 52 Mins - Same system as above.
Pro-6 ....... 4.2.27 .... 5 ....... 6 of 3 TB .... 13.60 TiB ..... 9 Hrs 45 Mins
RN312 ...... 6.2.2 ..... 1 ....... 2 of 2 TB ...... 1.8 TiB ...... 7 Hrs 36 Mins
RN516 .......6.2.2 ..... 6 ....... 6 of 2 TB ..... 7.68 TiB ..... 4 Hrs 53 Mins
Pro-6 ....... 5.3.3 ..... 5 ....... 6 Disks ....... 12.71 TiB .... 14 Hrs 10 Mins - Disk Info and Upgrade details in post below.
Pro-6 ....... 6.2.3 ..... 5 ....... 3 of 3 TB ...... 5.45 TiB .... 10 Hrs 40 Mins - Beta T1773, 8GB Ram, E7600 CPU@3.06ghz
Size, content, OS etc MAY be relevant as to why your system is different.
I hope this will be a useful post, that can help manage other peoples expectations.
PLEASE ADD YOUR DATA TO THIS POST especially if different model or RAID.
Note other similar posts on 'Volume Scheduled Options':-
Defrag - Find out how long? http://www.readynas.com/forum/viewtopic.php?f=21&t=80004
Balance - Find out how long? http://www.readynas.com/forum/viewtopic.php?f=11&t=80244
NAS Disk Test - Find out how long? http://www.readynas.com/forum/viewtopic.php?f=11&t=79874
One of these was Data Scrubbing.
Now having understood more about it, the obvious question is how long does it take.
I have now done two data scrubs and intend to do them every 3 or 4 months (gleaned from other posts).
The data below MAY be useful to new persons similar to myself and help people with their expectations.
So I suggest that those who are interested post their information as follows here, in the format below.
System ..... OS ....... RAID .... Disks ......... Total ........ Scrubbing time
RN516 ...... 6.2.2 .... 10 ....... 6 of 4 TB .... 10.90 TiB ... 17 Hrs 35 Mins - Identical time on 2 runs.
RN516 ...... 6.2.3 .... 10 ....... 6 of 4 TB .... 10.90 TiB ... 17 Hrs 52 Mins - Same system as above.
Pro-6 ....... 4.2.27 .... 5 ....... 6 of 3 TB .... 13.60 TiB ..... 9 Hrs 45 Mins
RN312 ...... 6.2.2 ..... 1 ....... 2 of 2 TB ...... 1.8 TiB ...... 7 Hrs 36 Mins
RN516 .......6.2.2 ..... 6 ....... 6 of 2 TB ..... 7.68 TiB ..... 4 Hrs 53 Mins
Pro-6 ....... 5.3.3 ..... 5 ....... 6 Disks ....... 12.71 TiB .... 14 Hrs 10 Mins - Disk Info and Upgrade details in post below.
Pro-6 ....... 6.2.3 ..... 5 ....... 3 of 3 TB ...... 5.45 TiB .... 10 Hrs 40 Mins - Beta T1773, 8GB Ram, E7600 CPU@3.06ghz
Size, content, OS etc MAY be relevant as to why your system is different.
I hope this will be a useful post, that can help manage other peoples expectations.
PLEASE ADD YOUR DATA TO THIS POST especially if different model or RAID.
Note other similar posts on 'Volume Scheduled Options':-
Defrag - Find out how long? http://www.readynas.com/forum/viewtopic.php?f=21&t=80004
Balance - Find out how long? http://www.readynas.com/forum/viewtopic.php?f=11&t=80244
NAS Disk Test - Find out how long? http://www.readynas.com/forum/viewtopic.php?f=11&t=79874
14 Replies
- Data is not relevant, as the scrub runs below the file system layer. An empty volume takes the same amount of time as a full one. Your total is volume size in TiB, so I adjusted the units. A scrub reads every sector (including parity or mirrored sectors), so raw disk capacity is more relevant than volume size (though that is easily obtained from the disk info). I added my info, and deleted the data column.
System ..... OS ...... RAID .... Disks ......... Total ........ Scrubbing time
RN516 ...... 6.2.2 ... 10 ....... 6 of 4 TB .... 10.90 TiB ... 17 Hrs 35 Mins
Pro-6 ....... 4.2.27 .. 5 ....... 6 of 3 TB .... 13.6 TiB ... 9 Hrs 45 Mins - Ok, I went for it anyway, and it seems the assessment on how long mine would take was waaaaaaay out (in a good way :) ):
System ..... OS ...... RAID .... Disks ......... Total ........ Scrubbing time
RN312 ...... 6.2.2 .... 1 ....... 2 of 2 TB .... 1.8 TiB ....... 7 Hrs 36 Mins
For some reason the scrubbing obviuosly starts very slowly, but must have speeded up overnight (see http://www.readynas.com/forum/viewtopic.php?f=21&t=80004 for background) - 516 6.2.2 raid 6 6x2tb 7.68tb ( or thereabouts) about 5 hours 4:53
- System ..... OS ....... RAID .... Disks ......... Total ........ Scrubbing time
Pro-6 ....... 6.3.3 .... 5 ....... 6 (see below).. 12.71 TiB ..... 14:10
Motley Disks, All Seagate
3x4 TB, 5900 rpm
1x3 TB, 7200 rpm
2x1.5 TB, 7200 rpm - these are the originals and as they act up, I have been replacing them. One has actually died (Seatools test failed); well past warranty. These are standard consumer issue disks! Great service I think.
FWIW, Pro 6 upgraded to Xeon CPU and 8 Meg RAM
[2015-04-06 Edit to correct OS version] - My addition:
System ..... OS ....... RAID .... Disks ......... Total ........ Scrubbing time ... Comments
Pro-6 ....... 6.2.3 .... 5 ........ 3 of 3 TB .... 5.45 TiB .... 10 Hrs 40 Mins .... Beta T1773, 8GB Ram, E7600 CPU@3.06ghz - My scheduled data scrub was last night and just finished a few minutes ago. The original post has been updated.
The NAS OS 6.2.3 seems to have taken 17 minutes longer than that for 6.2.2. (1.6% extra)
Probably not significant, although I had done 2 runs on 6.2.2 and they were identical to the minute. System ..... OS ....... RAID .... Disks ......... Total ........ Scrubbing time
RN516 ...... 6.2.4 .... 5 ....... 6 of 6 TB .... 27.17 TiB ... 1 day, 5 hours, 5 minutes and 44 secondsRan scrub for the first time since NAS installed (around November 2013).
System OS Raid Disc Usable Space Used Data SnapShot Free
RN104 6.4.1 5 (X-Raid) 3 * 1TB WD10EFRX-68JCSNO 1.81TB 828.95GB 330.97GB 692.38GB
Total time 66 Hours 47 Minutes
Oddly the first 26.67% took 51 hours 38 minutes with the remaining 73.33% taking only 15 hours 9 minutes.
Question – When using raid 5 with data striped across 3 spindles is it worth running the scrub utility?
Will now see how long the balance option takes or should it be defrag before balance? Beats me.
nickbatch wrote:
Question – When using raid 5 with data striped across 3 spindles is it worth running the scrub utility?Yes. The scrub reads all the files, and verifies the btrfs checksums. That is worth doing every now and then. I'd suggest a three month schedule.
nickbatch wrote:
Will now see how long the balance option takes or should it be defrag before balance? Beats me.
I don't think it matters much, as they do different things. It might be slightly better to do the defrag first.
Hi, here are some updated stats, we've spent time over new year putting in additional drives and changing the partitions, so we have a RAID10 partition that we use for iscsi connections and clustered storage. And a RAID1 partition that we use for backup so lots of data changing daily.
The scrub appears to be taken an inordinate amount of time, we expected that after the first scrub post significant data changes that the second scrub would be reduced. However, the first time was 4 1/2 days and a week after completion started again (so we could determine improvement or lack of) it is 5.51% complete after 20 hours.
System ..... OS ....... RAID .... Disks ......... Total ........ Used ......... Balance time ... Comments
A RN3220 . 6...4.1 .... 10.... 6 of 3 TB ...... 8 TB .........6 TB ..... 4 1/2 days. ........ Monthly
A RN3220 . 6...4.1 .... ..1.... 2 of 3 TB ...... 3 TB ... ..... 2TB ..... 15/16 hours. ........ Monthly
B RN3220 . 6...4.1 .... 10.... 6 of 3 TB ...... 8 TB ... .....6 TB ..... ? . ........ Monthly but not scheduled yet
B RN3220 . 6...4.1 .... ..1.... 2 of 3 TB ...... 3 TB ... .....1TB ..... 9 hours. ........ Montly but not scheduled yet
JGwilliam wrote:
Hi, here are some updated stats, we've spent time over new year putting in additional drives and changing the partitions, so we have a RAID10 partition that we use for iscsi connections and clustered storage. And a RAID1 partition that we use for backup so lots of data changing daily.
The scrub appears to be taken an inordinate amount of time, we expected that after the first scrub post significant data changes that the second scrub would be reduced. However, the first time was 4 1/2 days and a week after completion started again (so we could determine improvement or lack of) it is 5.51% complete after 20 hours.
System ..... OS ....... RAID .... Disks ......... Total ........ Used ......... Balance time ... Comments
The chart says balance time, not scrub time. Perhaps you can clarify?
Scrubs require reading every file/folder in the volume and verifying the btrfs checksums. A second balance or defrag should run much quicker than the first, but I don't see how the scrub time would improve (assuming no disk errors).
Some of the maintenance functions will suspend when disk spindown kicks in - I'm not sure if scrub is one of them or not. If you use spindown, try disabling it shortly before (or even during) the next scheduled scrub, and see if the times improve.
Hi, apologies I'd copied and pasted the details as I'd updated the three common threads (balance, scrub, defrag) but changed the times.
Disk spin down is not enabled on either system.
Thanks
Jo
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