Assessing the risks of RAID 5 before implementation

[it_geek]

Hi all,


I am considering going on a 4 x 2TB RAID 5 setup on a NETGEAR NAS.


Can anyone share their experience from a failed disk in RAID 5 and subsequent rebuilds? How long did the rebuild time take?

 

[yusoffb01]

So many points of failure. less headache to just buy 1 8tb and another spare for backup. less than sgd 200 during sales.

 

[existential_reality]

Have you tried this?

https://www.memset.com/resources/raid-calculator/

I run a RAID 6 but in your case I'm guessing safely is about 2 days to rebuild?

Hi all,


I am considering going on a 4 x 2TB RAID 5 setup on a NETGEAR NAS.


Can anyone share their experience from a failed disk in RAID 5 and subsequent rebuilds? How long did the rebuild time take?

 

[Songboh2102]

Around 1 day.... but rebuild is in the background. I have stnology nas in my office. Replace hdd once. Just rebuild

 

[Songboh2102]

So many points of failure. less headache to just buy 1 8tb and another spare for backup. less than sgd 200 during sales.

It depends...... if you dont use raid, hdd spoil means downtime.

 

[Songboh2102]

Wow... I am surprised no one has ever had to perform rebuilds on their RAID 5 before?

Me have, a few times for my coy server and once for synology nas. Basically iust replace hdd and a fee mouse clicks. Then wait.... 2TB should be less than 1 day.

I dont know exact time because i never monitor. Today change and rebuild. Come back office tomorrow done already... never check how long it takes.

But does it really matter?? Since nas supports hot plugging. Raid5 1 hdd fail also no data loss. No down time.

 

[jtjt00]

If you are sway, another HDD kaput during rebuild, data loss!

 

[Songboh2102]

If you are sway, another HDD kaput during rebuild, data loss!

Well, never face before..... 2 hdd failure in raid 5 i expeirence bit fail during rebuild never. If data is critical, you need at least 3 sets of backup

 

[Alphas]

I have RAID 5 on intel MB chipset. Its a 3x 1TB HDD (total 2 TB). Sometimes when windows does not shutdown cleanly, the RAID 5 will rebuild by itself, but it has never lost a bit of data.

 

[Songboh2102]

I do have data in long term storage in the form of LTO tapes. RAID is for data for the last 3 years but accessed infrequently


So 2TB about 1 day... must pray the remaining 3 disks can zng leh. Otherwise really become very problematic.

The RAID controller really got so slow, until like 20MB/s meh? Even if I leave it idling in the background? I was expecting rebuild speeds to be faster at 80 - 100MB/s , which is quite achievable with 7.2krpm drives. Even if I consider the parity overhead, having the speed reduced by 80% is quite ludicrous...

You can use raid 1 to avoid such problem. Then 3 x 8TB in raid 1, one down you still have 2.

 

[batniss]

When a RAID is being rebuilt, does the entire array have to be taken offline for the controller to perform the rebuild or will it still be kept online and accessible?

U can do it online and on the background. U can continue to use the drive just slower.

 

[talkonly]

In some cases raid 5 don’t work with 4 hard disk. If die die must use 4 hard disk then raid 1 lo.. rebuilding just swap in the new hard disk only

Hi all,


I am considering going on a 4 x 2TB RAID 5 setup on a NETGEAR NAS.


Can anyone share their experience from a failed disk in RAID 5 and subsequent rebuilds? How long did the rebuild time take?

 

[SGJoe86]

Are you using it for personal or work environment?
If using at work and data is critical, why not get a proper server with 24x7 support? Any time the HDD goes down, someone will be on the way with a new HDD.

 

[jtjt00]

I am intending to use 4 X 2TB in RAID 5.....

Similar to my ds418 setup, using 4x 2TB Toshiba HDD with SHR.

 

[terry1]

you do know what you are getting into :- this is a software raid and it is in a proprietary format

 

[HelloSensation]

Most consumer NAS don't even have a proper RAID card, so the implementation is almost always based on MDADM.

I'm using MDADM level 1 on my second-hand dual Xeon workstation.

 

[blackestvoid]

WOT
https://www.askdbmgt.com/why-raid5-should-be-avoided-at-all-costs.html

 

[talkonly]

Lol either you never read properly or your English is bad, I said some cases, not all.

I am surprised, this is the 1st time I have heard of RAID 5 and 4 disks not compatible...? I have an enterprise server from waaaaayyyy back, the RAID config was like this


All disks were ultra SCSI 320 15K RPM. Noisy as hell!!!


36.4GB x 2 - RAID 1 (OS - W2K Advanced Server, Later changed to CentOS)


73.8GB x 6 - HP RAID ADG/RAID 6 (DB1)


146.8GB x 4 - RAID 5 (ARCHIVE)


Worked fine for me, until the battery backed write cache was no longer in production or stock. That lesson was painful, took me 1 week of continuous running to get all of the data off. Surprisingly, the disks held on well for the 4 years it was running, save for one 73.8GB disk that failed and had to be replaced. One of the 146.8GB drives also showed signs of degradation.








Personal, for work I have another enterprise array for that, but I keep the array size really small (each disk about 500GB), running off enterprise SSDs.

 

[lifeislame]

Raid 5 read ok write is slow than raid 1

Sent from Samsung SM-G935F using GAGT

 

[-Synchronicity-]

If data is more important, can consider raid 6. If not raid 10 the best as you get much better read/write speed.