NAS Compares What is RAID? Understanding the Different RAID Levels for your NAS

What is RAID and why do I need it on my NAS Drive?

RAID is not a new thing. Originally created as means of combining multiple smaller hard drives and combining them into 1 large storage volume (so your PC would only see one hard drive like your C:/ drive, instead of several smaller hard drives connected). RAID stands for either Redundant Array of Inexpensive Disks, or Redundant Array of Independent Disks. Now the reason for the two different versions of the letters in RAID is largely due to how storage has changed. As Hard drives have grown progressively larger in capacity, the need for creating massive volumes has been outweighed by the more current trend of data storage arrays needing Redundancy.

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[jeyare]

Rob, Rob ... again and again mystified NAS newbies

Rob’s guide:
RAID0
... good read, good write speed ... vs his excellent evaluation for RAID5 speed
... By no means a long-term RAID solution

RAID1
... Requires at least 2 Drives and you can only RAID the Hard Drives in pairs
... Replacing a damaged or faulty hard drive is rarely possible whilst the enclosure is up and running. So you need to power down the unit/ NAS server to swap to hot swap a drive over

here I rather stop my review.
Really bad education article.
——————-
few recommendations or repairing of the mystifications:

RAID0
... is fastest possible RAID version, when you need really fast storage
... it is long-term RAID solution for those, who need such speed driven environment (e.g. heavy game 3D rendering, video rendering...)

RAID1
you don’t need pair of disk, you can use 2,3,4,5 disks .... up to your choice
3 disks RAID1 is an excellent alternative for fast & high redundancy of sensitive or valuable data (availability point of view) when you don’t have HA cluster. Also when you like and understand of data tiering advantages (right storage for right data).
And you can absolutely change new disk without power down of your NAS.

 

[WST16]

Alright Mr. RAID it all

What should I look for if I’m RAIDing SSDs in my NAS?
I know about TRIM. Aren’t they all TRIM enabled nowadays?
Is ok to use SSDs (ignore the price for now)?

Currently I’m using an SSD in the 118 and I really like it.
I found this on Quora. There’s an interesting comment about data recovery.

 

[jeyare]

re SSD and your link - clear enough and 100% agree. It sounds like my points re tiering vs hurray attitude to any disk/redundancy kind/...

Smart people never mix wine, vodka and beer in single glass or during single night. Same is valid for the disk usage in NAS.

 

[jeyare]

Re your 118, send me PM

 

[fredbert]

Smart people never mix wine, vodka and beer in single glass or during single night

Depends how late it is and when they started drinking

 

[jeyare]

of course Gents, this is another most important point to analyze
I remember for my first time in Edinburgh, or don't remember, never mind.
But the most important thing was that local chicks, uff it was kind of hurricane in speed of single-shoot spending per hour. Then I understood, that it was a race to midnight, when lights out. So no just the lights

 

[WST16]

Depends how late it is and when they started drinking

You woke up on the right side of the bed today, @fredbert

re SSD and your link - clear enough and 100% agree.

What’s confusing me a bit is Irné Bernard’s reply.

He says at the beginning (I’m copying here):
“Only if your NAS uses a decent file system like ZFS or BTRFS and doesn’t rely on old defunct RAID to combine disks. I.e. that throws away nearly all commercial NAS boxes.”

You can read his full reply (2nd one).

Re your 118, send me PM

No need for a PM!
This is what I have inside the 118. With this Fenlink converter.
Not exactly a top brand SSD. It’s working fine. But the 118 is not RAID, so it means nothing.

 

[jeyare]

still agree regarding the SSD in NAS. That was my similar point of view in past discussion here to use HDD instead SSD, because:
- you have still more limitations at CPU performance (SW based RAID), include encryption, include encrypted backups
- main board throughput limitations.
Then your biggest investment in NAS comes to disks. Best ever attitude is to take a break and take paper and pencil to draw expectations vs possibilities. One of my Resources is about it.

 

[jeyare]

8. With this Fenlink converter.
Not exactly a top brand SSD. It’s working fine. But the 118 is not RAID, so it means nothing.

You are right
the DS118 is single bay NAS, then you need forgot for RAID feature

re your disk:
- first - the disk is not in Synology compatibility list of SSD for your NAS

- you can forget for the official lazy "Synology support", but tested device is tested. Otherwise, few disks in the compatibility list for your NAS is really miniature. But who will spend months with testing for such market target.

- it is Micron 3D TLC NAND memory. Re TLC NAND:
Pros - Cheapest to manufacture which in turn leads to cheaper to market SSDs
Cons - Cells will survive considerably less read/write cycles compared to SLC or MLC NAND. This means that TLC flash is good for consumer use only (what is ok when some use this disk for such usage).

- Triple-Level Cell TLC NAND based SSDs perform usually quite well, but when you copy a large amount of data to the drive without and idle time you’ll often find a large drop in write speed. TLC NAND is great in applications where write operations are limited. In this point ADATA has better evaluation as Kingston or OCZ. Samsung is better.

- life cycle: TLC NAND has up to 5000 Read/Write Cycles for every single cell in the disk. Btw SLC has 20x more, then take into consideration when purchase SSD that purchase price is sometime misleading, check the technology inside (TLC, MLC, SLC)

- Mean time between failures (MTBF) is 2M hours = 228years for 7x24x365 operation. Forever

- at the official web I can't find info about TRIM or Garbage collection support for this disk. But follow this independent testers, it supports the TRIM.

- another test result for TRIM: Most SSDs today support the TRIM command, but we still run a quick test to ensure that the command is being properly passed through to the SSD and being done. A great free utility called TRIMCheck can be run to ensure that TRIM is functioning properly.

- this disk is supporting RAID usage

So, final stage:
- you can use TRIM feature for this disk
- you did perfect purchase (price/performance) when single file write operation is less than 1/3 of the disk data space

I don't know the major usage role of the NAS, then I can't tell you if you need HDD or SSD and what kind of. But the 1-bay NAS form factor - there is no question what kind of disk you need.

 

[WST16]

Thanks. Didn‘t know most of this
Although I knew that it’s not on the compatibility list. I didn’t care.

the 118 is an “experimental“ purchase for a small project. Running mail server, a simple website and offering documents exchange.

Of course the price/performance analysis on a larger SSD scale (4+ disks) is not compelling at all. Not a good value.
I just like the quietness and I think they generate less heat too.

 

[fredbert]

Had to check the RAM on the DS118 cos running Mail Server will take 400-500MB just to sit there when you've got AV (freshclam and clamd) enabled. An SSD should help if paging has to happen though the other two services aren't so heavy, probably.

 

[jeyare]

Many of TLC SSD disks have problem with small amount of SLC cache (integrated). Then the white paper write/teat speed is just shooting into dark. Then real performance is sometimes worse than in HDD. Specially when you move large amount of data.
Then is the disk tiering best way to performance.

 

[WST16]

It’s by no means under a heavy load at all (serving a team of 4). So far I’m amazed at what the 118 has been able to accomplish. I like its size, and with an SSD it’s so quite.

We’ll upgrade to a bigger DS once we go live, unless we decide to outsource the mail and web services.

 

[fredbert]

I'm sure. In fact the DS118 looks to be a great replacement for a Mac Mini server now that all the useful features of OS X server have been removed. Hang some USB disks off the back for extra storage and backup and it'll do really well.

 

[fredbert]

This has gone completely OT

But for a Mac Mini server replacement, depending on what you want to do, then it looks like:

1. Single disk: DS118 will do most (and more) things
2. Dual disk: DS218play for 2GB RAM
3. Dual disk and flexible applications: DS218+ gets you Docker and VM support, and up to 6GB RAM

And they are still a lot cheaper than Minis were before the price jump t'other year and the software is better too ... which says something coming from a "I've only ever bought Macs" person.

Now, back on topic, what was the conclusion on using dual SSD in these two-bay NAS? The comments I saw were binary yes/no. At present I see bulk storage is still on HDD so if that's the main task then use these, but if it's application performance then that's where SSD work best. And are DSXXXslim a good thing or pandering to the latest fashions?

 

[WST16]

Good points about the Mac mini comparison there.

I think the jury are still out on SSDs in NAS. The much higher prices –than mechanical HDs– are limiting the adoption. Most users will acknowledge that the bottleneck is the network and fall back to the cheaper mechanical disks.

Prices for 2TB SSDs on Amazon are around $250 now, 4TB at about $500. Still, not cheap, but prices are coming down and capacities are increasing.

 

[jeyare]

SSD yes, absolutely yes, but think twice:
- as you can see two different SSD can provide more performance, but also disappointment. TLC wit big SLC cache is better than TLC w/o such cache.
- then MLC is better than TLC for few coins more. do not hesitate to check amount of SLC cache also.
- pure SLC SSD is tornado, also for your pocket

There is still question about every kind of bottlenecks within data operation environment. Then SSD frequently is waiting for something outside.

A consideration- question is if you have SLC SSD if you need M.2 cache separately. Mathematically no, but there is missing a real test.