SSD+SSD+HDD RAID Configurations - Is speed with security possible?

Aegir

Limp Gawd
Joined
Apr 15, 2020
Messages
202
Two 1TB SSDs in RAID 0, with one 2TB HDD linking it into RAID 10.

How do I make sure that the speeds don't average out with the HDD?
How do I make sure that data is drawn from the SSD first?

I want the speed of two SSDs in RAID 0, but a backup HDD that can fit the entirety of both of them within it.
I want the backup to integrate smoothly into this solution, but I've never done any form of RAID before, so I'm not sure how to begin.

Any tips?
 
Joined
Dec 1, 2011
Messages
822
Oh man, no, that looks horrible. Don't do that.

No matter what, you will be bottlenecked by the HDD. A RAID subsystem, whether it be software (e.g., ZFS) or integrated into the HBA (i.e., a RAID card), will have to wait until an operation is complete before reporting such to the OS, and will usually try to spread any load across all volumes. So no matter what, it will always be waiting for the HDD. The times will not "average out", they'll reflect the slowest volume of the set.

RAID is not any kind of backup. At most, it offers some redundancy to help get you through a drive dying until a replacement can be installed. You need a proper backup application, preferably to a separate system or at least to a disk that can easily be detached (e.g., USB).

I'm guessing this is for your OS/system disk? Best bet is to use one SSD for the OS, the second for games or anything that would actually benefit from fast access, and the HDD for media (where fast access has little value) or as a backup volume. Don't put the SSDs into RAID 0 for the OS volume. All this will do is inflate worthless benchmarks, do nothing to improve access times/latency (where the real value of a SSD is), and effectively double the odds of a drive failure taking out your system. The only reason to run RAID 0 is as a scratch volume for specific workloads.
 

Aegir

Limp Gawd
Joined
Apr 15, 2020
Messages
202
Oh man, no, that looks horrible. Don't do that.



I'm guessing this is for your OS/system disk?
Thanks for the info.

This is actually for a NAS, but your points still stand.
So RAID with SSDs is pointless then? Especially for a NAS? 2.5 gigabit speeds.

Do you recommend I just get a single big SSD, and then have it backed up automatically to an equally sized HDD when file changes are detected or something?

The NAS will be on a fully functional PC, so it has some serious customization potential.

It's also down to a debate between my girlfriend and I. I want more speed, less latency, and pure performance.
She wants it safely secured and backed up.

And I only win if she wins, so whatever the solution is, it's gotta make her happy. Sigh.
 

likeman

Gawd
Joined
Aug 17, 2011
Messages
708
Two 1TB SSDs in RAID 0, with one 2TB HDD linking it into RAID 10.

How do I make sure that the speeds don't average out with the HDD?
How do I make sure that data is drawn from the SSD first?

I want the speed of two SSDs in RAID 0, but a backup HDD that can fit the entirety of both of them within it.
I want the backup to integrate smoothly into this solution, but I've never done any form of RAID before, so I'm not sure how to begin.

Any tips?
if your asking the question if i have never done raid before then you probably shouldn't do it, as your

if you booting windows just Buy 1 SSD that fits your size requirement like 500GB 1TB 2TB (do not raid 0 SSDs it's completely pointless)

you can't do RAID 10 with 1 HDD

what NAS are you using, need way more details of your plane and what you define as a NAS

if its Synology (4 bay nas or higher) then SHR2 (synology hybrid raid 2 disk redundant) RAID6 with 4 HDDs so you have redundancy (never use RAID5 or SHR1 unless you have a another backup) the newer synology units have 2 Nvme ssd slots that can be used for caching but not really needed if it's just a backup box
 

lopoetve

Imhotep
Joined
Oct 11, 2001
Messages
29,625
You can use SSDs as read/write caching depending on your filesystem and use case; you can't do what you're trying to do without some kind of synchronization mech that copies the data.
 

Nside

Limp Gawd
Joined
Jun 2, 2011
Messages
326
I would just set up a daily scheduled differential backup during typical downtime.
 

LFaWolf

Gawd
Joined
Aug 7, 2016
Messages
674
Use the 2x SSD in RAID 0 for speed, but have a daily backup to the 2TB HDD. If you have really important data, you should consider more backup options, perhaps cloud storage or at least another external drive which is quite cheap nowadays. Also, you should not have the SSDs and the HDD them in the same machine unless you have additional backup venues. What if you get a power surge, or if the power supply dies and takes out all the components in one shot?

What OS will you be running on the machine? FreeNas?
 

kalston

[H]ard|Gawd
Joined
Mar 10, 2011
Messages
1,095
Doesn't RAID-0 with SSDs actually do more harm than good anyway? Higher latency, no TRIM, and improvements in pure sequential speed which rarely even matters. I have stopped caring about RAID a while ago though, so could be wrong.
 
Joined
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Messages
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Doesn't RAID-0 with SSDs actually do more harm than good anyway? Higher latency, no TRIM, and improvements in pure sequential speed which rarely even matters. I have stopped caring about RAID a while ago though, so could be wrong.
All that, plus double the chance of losing the volume due to a failed drive.

About the only place for RAID 0 is for specific applications/workflows that require large/fast scratch volumes.
 

lilfiend

Supreme [H]ardness
Joined
Nov 28, 2008
Messages
6,477
Doesn't RAID-0 with SSDs actually do more harm than good anyway? Higher latency, no TRIM, and improvements in pure sequential speed which rarely even matters. I have stopped caring about RAID a while ago though, so could be wrong.
I was under the impression that trim has worked with raid 0 since haswell or so. I could be wrong.


I'm not sure what OS/enviroment OP is comfortable with or what the exact use case is for storage. The popular thing seems to be to use unraid/freenas to setup a zfs array. It is a low cost option that offers a lot of flexibility and real time redundancy (not backup). If your data doesn't change much and is fairly static, and you can deal with non-realtime redundancy, then snapraid + some sort of drive pooling could be a solution. I currently use drivebender + snapraid without issue. I've used primocache also to speed things up but its a little involved as you can't just point primocache at the mount point, you have to point it at each disk. I ditched primocache though and just moved everything that wasn't video to ssd's with 2 hdd's as parity drives. Snapraid's config file has settings for drive pooling so you could probably skip drivebender but I've not used that part of it at all so I've no clue how good/bad it is.

Drivebender on its own might be something too as you can mark folders/files for duplication (kinda like raid 1). It also supports a 'landing zone', which is really just a cache but it doesn't write-through to the hard drive until it runs the scheduled task that can be as often as every 5 min to just every day.
 

Ready4Dis

[H]ard|Gawd
Joined
Nov 4, 2015
Messages
1,761
Two 1TB SSDs in RAID 0, with one 2TB HDD linking it into RAID 10.

How do I make sure that the speeds don't average out with the HDD?
How do I make sure that data is drawn from the SSD first?

I want the speed of two SSDs in RAID 0, but a backup HDD that can fit the entirety of both of them within it.
I want the backup to integrate smoothly into this solution, but I've never done any form of RAID before, so I'm not sure how to begin.

Any tips?
Yeah, your better off with either scheduled back ups or some sort of directory mirroring that happens in the background. Only other option is setting some sort of tiered storage.
 

Aegir

Limp Gawd
Joined
Apr 15, 2020
Messages
202
Don't worry guys, I figured this out on day 2 of this thread's existence. =p

My current plan is one 2TB SSD and one 4TB HDD as a backup, all with a separate system drive as well.
 

likeman

Gawd
Joined
Aug 17, 2011
Messages
708
yep there is zero point in RAID-0 with SSDs (the added latency removes the actual benefits + you run the risk of the this RAID-0 just failing on your one day)

the people who need RAID-0 already know who you are (it has a Very specific use case, generally a scratch drive that requires high speed but really 1 NVME ssd on its own is norm enough for that)
 
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