Questions about raid

[A Lini]

I have heard about raid but have never understood it as in the benifits and how to do it also which version is best for what

so can anyone tell me advantages/disadvantages, how to set it up, and which version is best for a deticated NAS

[Levent]

make up your own mind.

[A Lini]

1 minute ago, Levent said:

make up your own mind.

thanks

[dalekphalm]

RAID is a method of combining multiple disks to achieve a task. The word "RAID" itself has two primary meanings:

 

1. Redundant Array of Inexpensive Disks

2. Redundant Array of Independent Disks

 

Reach RAID level serves a different purpose. Some RAID levels are no longer used, because new levels were created that serve the same purpose without some limitation.

 

Common RAID levels: RAID0, RAID1, RAID5, and RAID6.

 

RAID0 = taking multiple drives, and "spanning" them together - that is, to make one large virtual disk out of multiple smaller disks. It has 2 main benefits:

1. You get the combined space of all drives (assuming drives have the same capacity)

2. You get a performance boost for each drive you add into the array

RAID0 works by "striping" the data across all drives. That means when I write a file called "totallynotporn.mp4" to my RAID0 array, the file gets broken up into blocks (blocks are just chunks of data that make up the larger file), and the blocks are spread across all drives in a sequential pattern (Block 1 goes to drive 1, Block 2 goes to drive 2, Block 3 goes to drive 3, Block 4 goes back to drive 1, etc).

 

There are two massive downsides to RAID0:

1. There is no redundancy (despite the R in RAID). If one of the drives fails, your data is gone

2. Further to this, because it stripes the data, even the good HDD's now contain useless garbled data, because the file is not fully contained on any single drive.

 

RAID1 = taking multiple drives and mirroring them. This is to say that every drive in the array contains a copy of the exact same data.

 

The benefits of RAID1:

1. Your redundancy level is only limited by how many drives you stick into the array. Commonly, you'd put 2 drives into a RAID1, and if either of the drives die, the other good drive still has all the data. But in theory, you can add as many drives to this as you want. You could have a 10 drive RAID1 array, so 9 drives could fail and you'd still have your data.

2. Because data is on 2 (or more) different drives, you get a Read performance boost, as the RAID array can read data from multiple drives at once.

 

Downsides of RAID1:

1. The big one here is that you only get the capacity of a single drive, so it's very costly per GB of data.

2. The other big downside is that there's no write performance boost. On the flip side, there's no write penalty either. Write performance for RAID1 is identical to a single individual drive (or rather, is identical to the slowest drive in the array, if using different models of HDD).

 

RAID1 is very common for Boot Drives in enterprise environments. Especially on servers.

 

RAID5 = Taking 3 or more drives and spanning them together to create a large drive. The difference between 0 and 5 is that 5 has "one disk redundancy", meaning a single HDD can fail, and the array is still okay. It accomplishes this by taking a single drives worth of space (spread out across all drives) and uses that space to create Parity Data calculations (data calculations used to rebuild missing data from a single dead drive). Like RAID0, data is striped across all drives sequentially.

 

RAID5 has a write performance loss due to having to not only write the data file, but also write the corresponding parity file too.

 

RAID6 = Taking 4 or more drives and spanning them together in the same manner as RAID5, with the sole difference being 2-drive redundancy instead of 1-drive redundancy. It accomplishes this by spreading 2-drives worth of Parity calculations onto the array.

 

RAID6 has an even worse write performance loss due to having to write two parity calculations for every file, but it can also sustain 2 drive failures and keep working.

 

There's also nested RAID levels, in which you essentially RAID a RAID - Examples of this would be RAID10, RAID50, and RAID60. In the case of these, you're basically taking two (usually identical) normal RAID arrays, and then doing a RAID0 span between them.

 

There are also "RAID-like" arrays. This would include software "RAID", such as Windows Storage Spaces and ZFS (which has a different name for them - RAIDZ1 = RAID5, RAIDZ2 = RAID6). There's also stuff like unRAID and FlexRAID too.

[Salv8 (sam)]

39 minutes ago, dalekphalm said:

RAID0

thats why they call it RAID 0, 0 chance of getting your data back!

[dalekphalm]

4 minutes ago, Salv8 (sam) said:

thats why they call it RAID 0, 0 chance of getting your data back!

So true my friend, so true.

 

I cringe every time a user on here posts about their RAID0 SSD arrays, etc. Especially since we know most of them aren't doing regular backups

[Salv8 (sam)]

2 minutes ago, dalekphalm said:

I cringe every time a user on here posts about their RAID0 SSD arrays, etc. Especially since we know most of them aren't doing regular backups

my server can't even do it, i want one so i can use it as a cache for my OS and plex to speed up loading up media...

[dalekphalm]

Just now, Salv8 (sam) said:

my server can't even do it, i want one so i can use it as a cache for my OS and plex to speed up loading up media...

You could probably do it in Windows using Spanning - but I can't imagine the performance boost would be as good.

 

I'd actually like to put a bigger Plex cache on SSD at some point. Right now I'm using a 50GB VHD off of my 120GB ESXi boot SSD.

[Salv8 (sam)]

2 minutes ago, dalekphalm said:

You could probably do it in Windows using Spanning - but I can't imagine the performance boost would be as good.

can't span, the RAID card won't let the OS see the drives as separate like a HBA, it's Raid0 is like a Raid5 but without redundancy, but it's still technically a Raid5 because it's still doing things Raid5 would do, just without redundancy, IBM is weird man..

[dalekphalm]

Just now, Salv8 (sam) said:

can't span, the RAID card won't let the OS see the drives as separate like a HBA, it's Raid0 is like a Raid5 but without redundancy, but it's still technically a Raid5 because it's still doing things Raid5 would do, just without redundancy, IBM is weird man..

Does your server have regular SATA ports on the motherboard? Mine (Dell T410) does, and that's how my boot SSD (and by extension, Plex VHD cache) is connected.

[A Lini]

Thank you for the help

would you reccomend I get a dedicated NAS or just have a RAID array in my pc

if I had a RAID array I would be using it for some 1080p - 1440p videos I edit and photos that could range from 720p to 4k along with some programs I don't use very often. 

[dalekphalm]

1 minute ago, A Lini said:

Thank you for the help

would you reccomend I get a dedicated NAS or just have a RAID array in my pc

if I had a RAID array I would be using it for some 1080p - 1440p videos I edit and photos that could range from 720p to 4k along with some programs I don't use very often. 

Whether you have a separate NAS or build an array inside your main PC is personal preference. I prefer to separate things out, and I have a home file server running FreeNAS in a virtual machine.

 

The benefit of a separate NAS is that it's available all the time (Even if your main PC is off), and it can potentially fill other roles as needed.

 

You could purchase a cheap 2-Bay QNAP or Synology NAS and drop a couple of large HDD's in there for starters - or build your own "NAS" using used components. Or even buy a used server off of eBay (be weary of shipping costs, and do your research before buying).

 

If you're going to create a RAID array in your own PC, you're probably better off buying a used hardware RAID Card (ensure it has RAM cache + battery unit).

 

If you're going to build a NAS, you have a lot more flexibility, and likely don't even need a RAID Card at all, especially if you use a NAS OS like FreeNAS or unRAID or ProxMox or even Windows Server.

 

There's a lot to consider.

[A Lini]

2 hours ago, dalekphalm said:

Whether you have a separate NAS or build an array inside your main PC is personal preference. I prefer to separate things out, and I have a home file server running FreeNAS in a virtual machine.

 

The benefit of a separate NAS is that it's available all the time (Even if your main PC is off), and it can potentially fill other roles as needed.

 

You could purchase a cheap 2-Bay QNAP or Synology NAS and drop a couple of large HDD's in there for starters - or build your own "NAS" using used components. Or even buy a used server off of eBay (be weary of shipping costs, and do your research before buying).

 

If you're going to create a RAID array in your own PC, you're probably better off buying a used hardware RAID Card (ensure it has RAM cache + battery unit).

 

If you're going to build a NAS, you have a lot more flexibility, and likely don't even need a RAID Card at all, especially if you use a NAS OS like FreeNAS or unRAID or ProxMox or even Windows Server.

 

There's a lot to consider.

Thank you for the advice from what you said I think I want to build a NAS as while I could afford a raid card I'm running out of PCIE slots on my Motherboard

[Salv8 (sam)]

6 hours ago, dalekphalm said:

Does your server have regular SATA ports on the motherboard? Mine (Dell T410) does, and that's how my boot SSD (and by extension, Plex VHD cache) is connected.

nope, the motherboard's sata controller died, everything is running though the raid controller...