Hey everyone. So I’m trying to decide which RAID should I choose for my 6trays NAS. I have 4 x 16TB HDDs, 1x8TB HDD and another one 500GB ssd that I will use as a containers’ docker folder usage. I will be using the NAS to store Media files (movies, tv series, photos, music etc.) and also documents. Currently I have the 2 16tb as RAID 1 that only the Media files are stored and I am in between either creating another RAID 1 with the remaining 2 16Tbs or adding them to the other 2 to create a RAID 5 and have a bigger storage pool Have you had any incident where 2 HDDs were lost-damaged simultaneously (as RAID 5 forgives loss of only 1 drive) or not?
In addition I was thinking of having the 8TB HDD as a standalone to backup the documents and maybe the photos and the docker setups.
Does this make sense to anyone that uses similar setup?
Thanks for your inputs!
Odds are strongly against a 2 drive failure at your scale, though it does happen. I set my NAS up about 8 years ago, with 6 drives with raid-6 (well zfs’s version) and in that time two drives have failed years apart. When you get two hundreds of drives total in your operation you will see a dual drive failure.
Though you still really should have backups of everything you care about. Even though odds are in your favor someone reading this will lose data in their life on their NAS system.
In the last 25 years working with approximately 700 servers that used RAID 5 I saw two of them lose an entire volume. Once was due to a malfunctioning HP RAID controller, and the other was due to a second disk dying while the rebuild from the first failure was still ongoing. There turned out to be a systemic problem with that drive model’s firmware which almost certainly contributed.
So in my experience it’s rare but it definitely does happen.
It can get worse. About 20 years ago the company I was at had an EMC tech yank the wrong power supply from a Symmetrix rack, where the other supply had earlier in the day caught fire! We lost that entire rack’s data (customer’s personal email accounts) due to data corruption. It was probably around 300 10k SCSI disks in that rack, a multimillion dollar expense at the time, and we had to restore all of it from tape over many, many days. Really, really sucked.
Use zfs, raid 10 the big drives, toss the 8tb, and use the ssd as a write cache.
Interesting take. I have them setup in BTRFS and use 2 m2 nvmes as read write cache in RAID 1.
This is the way to go. Way more flexible than hardware raid and getting better all the time.
In ZFS-speak, instead of RAID 10 you’ll be doing “mirrored vdevs”
I’m fine with RAID5. Though I’ve seen the case where one drive failed and another one had several bad sectors and maybe was at the brink of failure, too. We were able to rebuild the RAID and replace both drives succesively but lost a few files. I think chances are slim, though. And even with RAID6, chances are your house burns down or lightning hits the neighborhood or a thief breaks in and takes the entire server. Or you or someone deletes stuff. So it doesn’t really replace a backup in any case. I’d say RAID5 is fine for home use. Take backups of your most important files.
Personally I use RAID5, with regular backups for documents and projects. Not too worried if my movies and tv library get lost…that takes up most of the space though.
Personally I’m more on the paranoid side, so I went with raid 6 and a hot spare. So in case of failure I can rebuild one disk immediately and not having to buy one first. But so far I’ve never had a disk failure.
In addition I was thinking of having the 8TB HDD as a standalone to backup the documents and maybe the photos and the docker setups.
That is a very good idea. I also can’t quite afford to backup my main storage of movies/shows, but at least all the important personal documents (and my music) is properly backed up.
