Updating My Aging Synology NAS - Help with 2 Questions?

Click_It on 09/02/2020 - 13:43
Last edited 20/02/2020 - 08:49

Before we start, someone always drops in just to say RAID is not a BACKUP, this assumes backups are already in place so there is the door!

QUESTION 1: Which RAID?

I have the following:

  • DS1813+ (2013) - 6 x 4TB
  • DS1511+ (2011) - 5 x 2TB

Both run in SHR-2 (Synology's hybrid RAID-6 for those unaware) which allow adding different sizes, so essentially I could start adding new drives 1 by 1. That's the best solution if you like to grow an array with larger drives later.

The downsides of a RAID-6/SHR-2 is rebuild times. When using multiple 10 or 12TB drives we could be talking a week or more.

Alternatives?

  • RAID-1 - Technically safer than RAID-10 but in real terms I'm not sure how common it is outside of 2 bay arrays today
  • RAID-5 - Less redundancy v RAID-6 (1 drive instead of 2) but faster all round and can still be migrated to R6 later.
  • RAID-10 - Mirrored and striped makes it the fastest option by far! Though if you lose 2 drives on the same mirror you are hosed.

QUESTION 2: Which NAS?

My NAS boxes are aging. I've heard recent reports of DS1813+'s failing due to motherboard issues. The good news is, if it dies beyond repair I can move the drives into a new NAS box and restore the data, but that's something I'd rather avoid.

If buying a new NAS I'd get the DS1618+. As a bonus it offers 10GbE or SSD caching addon.

UPDATE / CONCLUSION

I've personally decided to get a new DS1618+ (6 bay) and start with 4 x 12TB drives in RAID-5. Expand to 6 later. I'm not using SHR technology as I prefer to rebuild from scratch and by then 20-30TB drives will be readily available. Added bonus, I can use BTRFS which has a performance tax but much safer for data. I will also throw in ECC RAM despite it most likely being unnecessary, just because I can (it's cheap).

Alternative NAS I almost considered was the Asustor LockerStor 6208T. Superior in every regard for features (4 x 10GbE plus SSD caching!) but I've heard a few reports suggesting they are less reliable than Synology. I know Synology are rock solid so ultimately that's most important to me.

I hope this has been helpful for others.

Computing

Comments

  • devpress on 09/02/2020 - 14:02
    +1

    keen to know as well

  • smashman42 on 09/02/2020 - 14:35

    Well, obvious pros & cons for the RAID 1 vs 10…

    Capacity is the same

    RAID 10 is potentially faster (more so for more drives, duh)

    RAID 1 and 10 from a single drive failure only rebuild a single drive, so no difference (the older RAID 0+1 stripe and mirror wasn't as smart & rebuilt the whole stripe)

    Not seeing a down side to RAID 10 here vs RAID 1(Have I missed something?)
    If you have four or more drives, why the hell not?

    • Click_It on 09/02/2020 - 14:41

      Basically that's my take on RAID 10 v 1 too.

      My understanding of RAID 10:

      In RAID 10 each mirror is striped, you can lose 1 drive in each of those mirrors before you have a problem. So the only problem lies if you have a whole mirror wiped out, that's gotta be rare and probably safer than my RAID-6 which has always been good to me. It's only larger drive capacity pushing me along from that arrangement. I'm not sure if RAID-1 is any safer actually, just without the striped performance?

      I will initially have 4 drives but ultimately 8.

      • smashman42 on 10/02/2020 - 14:46

        I've got the same conundrum coming up, shifting from a pissweak 4 bay arm based Readynas with 3x 4tb drives to a homebuilt i5 server/NAS combo with 8TB drives & SSDs for write caching (half the parts either already here or on the way)

        Have always used RAID5 but the rebuild time even with more CPU grunt is off putting, so looking at a mirror for now then whether I upgrade to RAID 10 when I get more drives or just add more mirrored pairs.

        The only way I can see RAID 1 being safer is if you have the matching drives simultaneously die in both stripes, breaking the whole array and losing everything. With RAID 1 instead of 10 you'd only lose that mirror pair and everything else would be fine. But then RAID 10 could match RAID 6 in a couple of weird two drive failures where it could recover, two non-matching drives from each stripe and it'll rebuild just like a pair of mirrors would, plus the striping overheads.

        • Click_It on 10/02/2020 - 18:50

          Thanks for sharing. That's a good argument case for RAID 1.

          I'm a little confused at the moment. The folks at synology are pro RAID 5 which I'm trying to get my head around. If I want parity with a large array, I see RAID 6 as the better option. Maybe they don't like 6 because its slower. Rebuilds will also be slower and more stressful so there's that…

          Otherwise RAID 1/10 is a smart move. In my situation I'll be buying 4 straight away so RAID1, 6 or 10 starts me off with the same usable space.

          • smashman42 on 11/02/2020 - 15:07

            @Click_It: It depends on what your needs are, do you actually need more performance than a single drive anyway, and is read or write more critical?

            They're probably all RAID 5 for the most efficient drives to capacity ratio with still a drive worth of redundancy, plus a reasonable mix of more read performance and not too much write downside.

            If you can afford/want more redundancy, then it tips into do you need read speed so R6, or is write more important so R10/R1?

            They're probably lowest common denominator-ing it, plus what they're used to is the best because that's what they've always done.

            In a lot of cases, R5 with an extra external backup is better for disaster recovery than R6, too. Depends on how you look at things. I'm planning to have the new unit backing up to the old unit at a mate's place over a VPN with RSync running overnight, plus a couple of external drives locally for an alternating backup pattern to protect a bit more from stuff being locked by ransomware (snapshots only protect it if you have enough free space for everything to be on the drives twice over, once encrypted & once before they got in), then there's the extra critical stuff going to the cloud drives too.

            Kinda overkill for a home user eh? Still ain't nothin on those homelab guys

            • Click_It on 11/02/2020 - 16:05

              @smashman42: Thanks for the info!

              Read speed concerns me more than write. I pretty much park data on the RAID and it stays there forever.

              This might sound weird but I'm wondering if 2 x 32TB R5's might be better than 1 x 72TB R6. Purely from a rebuild time perspective, am I overthinking this now? :)

              I have on-site and off-site backups for critical data. But a good proportion of the rest won't be backed up until HDD prices come down further. So I'll be taking a few chances in the first 1-2 years. My critical stuff is always safe though.

              • smashman42 on 11/02/2020 - 16:43
                +1

                @Click_It: Shorter rebuild time and the benefit of half the disks being situation normal after a single drive failure, it doesn't sound that bad of an idea to me.

                Plus if you only build one array now and the other is planned later for an upgrade, it wouldn't lock you into 12TB drives, you could go up or down depending on your budget and the market at the time.

  • CyberMurning on 09/02/2020 - 16:15

    I have DS1511+ (2011) too but no plan to upgrade. Synology is too expensive.

    • Click_It on 09/02/2020 - 16:23

      I need to clarify the drives can be safely migrated to another Synology NAS in the event of NAS Failure. If so, I'll probably keep what I have (maybe sell the DS1511+ to offset costs) and just upgrade HDDs

      • jnewau on 09/02/2020 - 16:47
        +1

        Yes you can do this without problems. You don’t even need to keep the drives in the same bay order, as long as you swap all drives In the volume you’ll be fine as the raid set information is recorded on each drive.

        • Click_It on 09/02/2020 - 17:01

          Legend. I think you just saved me $1200 in that case. May as well upgrade when I have a definitive reason to, and by then there might be newer/better NAS options.

  • Click_It on 10/02/2020 - 10:48

    Update: Firstly I should state, I'm not doing this upgrade until May so I have time on my side to research this properly, a good amount of information should end up here which I can eventually put back into the OP for others to refer to in future.

    So I also posted this on the Synology Forums and was surprised with the response. Predominantly they're saying use SHR (Hybrid RAID-5!). To me that's not acceptable for an eventual 8*12TB array, but RAID-6 maybe…

    RAID 10? Their argument against it is that I'd never see the full performance unless I go full 10GbE and even then, the Atom CPU will hold me back. Although that only half answered my question. Ultimately I don't care about performance as much as reducing load on the drives. RAID-10 still achieves that goal. One downside (albeit rare) is RAID-10 could be hosed with just 2 drive failures if you're unlucky to suffer them both on the 1 mirror. RAID-6 has a hypothetical advantage there.

    SHR2 vs RAID-6: I currently run SHR2 but I'm not using it for its key feature (growing drives sizes) so I wondered what I'm losing compared to native RAID-6 and the answer is performance. I've seen tests showing RAID-6 up to 5x faster than SHR2 (non-encrypted vs SHR2 encrypted) so SHR2 is definitely out. What I'm not sure about yet is if SHR2 is harder on the drives than RAID-6. I think it is but can't find evidence to back that up yet.

    My options are down to RAID-6 and RAID-10

    • RAID-6: Cheaper
    • RAID-10: Expensive but lighter load on HDDs may preserve them longer

    Off topic (for me), I found out ZFS apparently has a 3 drive redundancy mode which might an option for some but Synology doesn't support it so I can't include that here.

    My opinion on RAID-5 and RAID-6 was influenced by that belief circulating the internet that RAID-5 becomes useless after 2009 and RAID-6 after 2019. It's based on mathematics that unrecoverable read error rate (URE) of 10^14. I won't go into it here but I've discovered it's likely flawed logic. The maths is right, the premise is probably wrong. This guy goes into it a little. I'm mentioning this because that was my primary reason for leaving RAID-6 behind. Now maybe I don't have to!

    ECC RAM, what I might do though is change my DS1813+ RAM over to ECC for some extra protection (automatically detects and corrects memory errors)

    I'll keep updating with my findings and thinking process and welcome feedback along the way.

  • Click_It on 14/02/2020 - 09:42

    Another update.

    I've decided I will sell my NAS boxes and buy a DS1618+ and build a 4 drive (36TB usable space) RAID-5 array upgradable to 60TB, or 48TB RAID-6 which I could migrate to later. Those capacities will see me good for many years.

    The newer NAS gives me BTRFS for some extra peace of mind.

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