ReadyNAS 516 + 2x EDA500 - Scrub on EDA500 very slow
I am trying to be dilligent on filesytem maintenance and disk tests to prevent issues going forward. I have scheduled, every 4 months each of the following maintenance operation on the different volumes:
Disk Test
Scrub
Defrag
Balance
My system is running on a RN516 (6.5.0) with 6x WE30EFRX 3TB drives, an EDA500 plugged into SATA port 1 with 5x WD60EFRX 6TB drives, and another EDA500 plugged into SATA port 2 with 6x WD60EFRX 6TB drives. I have a volume vol1 on the internally connected drives, vol2 on the 1st EDA500, and vol4 on the 2nd EDA500 running Flex-Raid - all RAID6. I can successfully run a defrag, balance and disk test on all volumes as expected. I can successfully run a scrub on vol1 (internal disks), but when I try to run a scrub on the EDA500 volumes it is so slow it will never finish. After days vol4 was at < 1%, so I cancelled it. This morning I started a scrub on vol2 and it has been running for hours and it is less than 1%. The scrub on the internal vol1 completed the 10TB scrub in about 18 hours (great), the EDA500's would be weeks and weeks, and performance during the scrub is terrible.
Can you help me troubleshoot what is causing the issue and how I can speed up the scrub process as i don't want to put the data at risk. There is no real feasible way for me to backup 40-50TB of data. I am planning on getting a new RN316 with 6X 8TB drives and configure RAID5, but it wont be until March next year. After that I can sync the critical data and rebuild if necessary, but for now I would like to fix thie problem.
Not sure if it is relevant, but I am also configured to LACP 3+4 with a Cisco 4948 switch.
Please let me know if you need any more information or can help in any way.
Re: ReadyNAS 516 + 2x EDA500 - Scrub on EDA500 very slow
So now, after 36 hours running a scrub on an EDA500 volume (vol2) the process is only at 4.24%. The volume is 5x WD60EFRX in RAID6 configuration (16TB). This is really un-usable with the current performance. If I lost a drive and it took over 30 days to rebuild the volume the risk is very high to lose the data. I need to understand why it is so slow and speed it up, or I need to find another array that will work properly. The drives in the RN516 are WD30EFRX in RAID 6 and the scrub on it ran to completion in about 18 hours, why is the EDA500 so slow?
Re: ReadyNAS 516 + 2x EDA500 - Scrub on EDA500 very slow
Good question.
The volume I have been trying to scrub is on an EDA500 (external chassis) plugged into a RN516. The volume is 16.1TB in size and there are 6.49TB free. Keep in mind that I can scrub a volume that is NOT on the external chassis, 10.9TB in size, in about 18 hours total.
Re: ReadyNAS 516 + 2x EDA500 - Scrub on EDA500 very slow
Thanks for the info sharing.
18 hours of scrub for 9 Tb in RAID-6 quite fast. This is not real fast for me. Elapsed time for scrub operation and volume synchronization sould be identical.
RN516 has more power processor than ULTRA6 and I can not compare them. Could you check CPU performance over SSH using 'top' or 'htop' command for vol1,vol2,vol4 scrub please?
Next point. If you are ready for this experiment. You can replace internal vol1 to vol2 or vol4 and check scrub performance without EDA500. Vol2,4 have OS6 installed into OS partition and OS6 will be restricted with apps only (they are on vol1). The scrub is the part of OS and should be working.
Next point. I use my EDA500 for backup copies with differend HDD volumes. You can do the same if replace HDD for backup in one of the EDA500. In this case you don't need additional NAS (additional HDDs only). More cheaper solution. Backup operation is more fast operation than scrub. rsync is the best for this. It will copy differences only.
