Advantages/Disadvantages of Synology Hybrid Raid?

[nutmegio]

You won't have a button for Quick/Custom format, it's an option you see after you click on the Create button.

Can you please report what's your current situation?
Go to Storage Manager, Volume tab, and see how many volumes you have, what Type they are (SHR without data redundancy or with 1-disk redundancy) and how many disks are in use for them (they are listed under the volume usage 'pie chart'.
Note: if while checking the volume status you see the 'Create' button disabled, that's also a sign that all disks are already in use.

This is my current config;

DSM 4.0

Storage Manager...Volume tab....Volume 1 properties;

Synology Hybrid RAID (SHR) (With data protection of 1 disk fault-tolerance)
File System: Ext 4
Status: Normal
Capacity: 1.79TB
Used: 322.77MB
Available: 1.79TB

Disk Info
DS212J Disk1 1.82TB Normal
DS212J Disk2 1.82TB Normal


Create button is disabled as per above scenario: I have one SHR volume using two disks (see above)

If you see that you have again one SHR volume using two disks, the easiest solution is to start from scratch. Go to control Panel -> Restore Defaults and select 'Format the hard disk but keep the current settings'. Status LED will begin to blink in amber color.
Now open Storage Manager. It should offer both Quick and Custom options.

So I'm starting from scratch as recommended above.


I have selected the " Format the hard disk but keep the current settings" option.

If you choose Quick, at the next screen select only one disk, then proceed with creating the first volume, then return to Storage Manager and click Create button to create the second volume. Do not touch the Manage button.
If you select Custom option, use the 'single volume on RAID' option, select only one disk and then choose 'Basic' type. Then proceed as described above to create the second volume.

I now have the following 2 volume setup; after selecting the "Quick Option"


Volume 1
Synology Hybrid RAID (SHR) (Without data protection)
File System: Ext 4
Status: Normal
Capacity: 1.79TB
Used: 322.77MB
Available: 1.79TB

Disk Info
DS212J Disk1 1.82TB Normal



Volume 2
Synology Hybrid RAID (SHR) (Without data protection)
File System: Ext 4
Status: Normal
Capacity: 1.79TB
Used: 322.77MB
Available: 1.79TB

Disk Info
DS212J Disk2 1.82TB Normal



Many thanks Maxxfi your instruction has been clear and concise.

[sursan]

Hello,

I have some questions. I have a DS409 with 2 x 2 TB disks, RAID 1 (one volume).

I plan to add two more disks. If I go for RAID 10, I understand I need to add 2 more disks of 2 TB each, which could be fine.

However, I see that today even disks of 4 TB are supported for my DS. Looking at Synology documentation, in RAID 10 configuration I will still use only 2 TB from each new drive, for a total space of 4 TB, which is a waste.

I don't really get this RAID limitation, why I cannot have 2 x 2 TB + 2 x 4 TB in a RAID 10 configuration, but let's accept it. Can SHR can help here to get 6 TB fully mirrored? Do I need to rebuild my volume or restore it is fine? (I have originally built this volume with DSM 2.2 I think, but now I have DSM 4.0)

Another thing, I use this DS at home (store data, music, movies which I use in a network from 3 - 4 computers, sometimes 2 at the same time), so I don't need huge performance, but I am kind of maniac with the mirroring. With two drives I didn't have too much choice, but with 4 drives (2 x 2 TB + 2 x 4 TB or 4 x 2 TB), what is the best option?

One more thing, since I am adding these drives 3 years or so later, I am not sure I will find exactly the same HDD model. If the best way is to add 2 x 2 TB drives, should I use the same manufacturer (Hitachi) or any other should do it? Also, the two drives I have are in the "Desktop" category according to Synology, is this that bad in a RAID environment ("Enterprise" category recommended).

Oops, quite a long post, with a lot of question and only one related to SHR, please don't kill me

Thank you in advance!

[HarryPotter]

The so called "limitation" has nothing to do with Synology, it is how RAID works in general.

SHR is the better choice in this case, but you still waste space (formula is total size minus biggest size => 2x2TB + 2x4TB = 8 TB), and yes, you have to rebuild the volume.

Why are you maniac with the mirroring? RAID is no backup solution at all!

You can mix different brands.

[sursan]

Thank you for your answer!

I agree it is not a Synology limitation.

Why is SHR a better choice than RAID 10 in this case, if the final capacity is still 4 TB, just like RAID 10?

About mirroring, I agree it is not a backup solution. But, let's face it, what are the options for a home user?
- backup your NAS data on DVDs - for 1 TB, you need more than 200 DVDs
- backup on an external disk - well, this is not too much different than RAID 1 or 10
- backup on a tape - quite expensive for just home data

Honestly, RAID 1 or 10 is quite good option since one disk failure is easily recoverable (and with some quality products, the probability to lose 2 disks at the same time is quite low). For 1-3 TB of data, with 4 disks of 2 TB, the solution is not too expensive (at least for me now, I just need to add two more disks) and it has 0 administration costs.

Maybe I'm wrong, I am opened to other suggestions!

[HarryPotter]

backup on an external disk - well, this is not too much different than RAID 1 or 10

Of course it is total different. First you still have the data if you delete data accidentally, 2nd you can keep a backup on another place, 3rd you can read the backup data anytime on another computer and so on.

In a RAID10 all 4 disks are considered being same size as the smallest one => you get 4 x 2 TB, mirrored = 4 TB

In a SHR volume you get total size minus biggest size => you get 2 x 2 TB + 2 x 4 TB - 4 TB = 8 TB with 1 disk redundancy.

I still cant undersatand why people are maniac about mirroring unless they need as much uptime as possible. For backup the only reasonable solution is an external one.

[Captain Awesome]

Hey all,
Just ordered my first Synology NAS, should get it next week. I had posted over in the performance forum with a number of questions (link), but I think one of the answers might lie in what I'm reading in this thread.

2) What's the fastest way to transfer my nearly 4TB of data to the NAS once it's setup? Should I transfer it all over to the G-RAID via the eSata ports (on my desktop and the external drive) and then transfer from the G-RAID to the NAS via the eSata ports on those machines? Or, given the bottleneck of my FIOS router, should I move my desktop onto the Netgear router with the NAS and transfer it over the network?

Based on what I've read here it sounds like I HAVE to transfer the data from my current 2x2TB drives to the external drive first, as I will need to have those drives installed in the NAS when I create the SHR+1 volume (as the 2x2TB drives are smaller than the 2x4TB drives I will also be using in the NAS). Is that accurate? Or can I setup the volume with the 2x4TB drives, transfer the data, and then add the cleared 2x2TB drives to the array?

[maxxfi]

Or can I setup the volume with the 2x4TB drives, transfer the data, and then add the cleared 2x2TB drives to the array?

No, you cannot. For both normal RAIDs and SHR, what matters, and determines the 'building block size' of the array are the initial disks, so if you begin with 4TB drives, you can only add 4TB (or bigger, when they'll exist) drives to the array.

If you don't have it yet, I recommend that you get a gigabit switch for you internal LAN.

[Captain Awesome]

Or can I setup the volume with the 2x4TB drives, transfer the data, and then add the cleared 2x2TB drives to the array?

No, you cannot. For both normal RAIDs and SHR, what matters, and determines the 'building block size' of the array are the initial disks, so if you begin with 4TB drives, you can only add 4TB (or bigger, when they'll exist) drives to the array.

If you don't have it yet, I recommend that you get a gigabit switch for you internal LAN.

Thanks for the response. Very glad I found this thread first and glad I ordered that 8GB external drive.

Another question on this topic: It seems that I read in here that using the smaller drives creates small blocks and is, thus, less efficient leading to slower read/write speeds. If you do go with 2x4TB + 2x2TB in the array and later replace both of the 2TB drives with 4TB drives, does it alter the "building block size" of the array? Or do I still have the more inefficient array structure? With 2TB vs 4TB drives am I even likely to notice any differences in speed either way?

[maxxfi]

Well, the 'small block', in case of a 2TB drive, is as small as 2TB so I wouldn't worry about any sensible loss of performance.

[HDClown]

Picked up a DS1512+ today and have it loaded with 4x3TB drives and newest DSM build. I want 2 disk redundancy, and the ability to expand the volume at a later date by adding a 5th drive and I'm trying to determine if I should choose SHR or RAID6. So, some questions:

1) If I choose SHR w/2 disk redundancy, and add a 5th 3TB drive, can I expand the volume just like I could if I choose RAID6?

2) If I choose SHR w/2 disk redundancy, and add a 5th drive that is 4TB drive, can I expand the volume and utilize the extra 1TB of space on the 4TB drive (vs. RAID6 which would not) ?

3) If I choose SHR w/2 disk redundancy, add a 5th 3TB drive and expand the volume, and then want to start replacing 3TB disk with 4TB disks at a later date, can I do this and maintain all usable space?

From what I've read of SHR, the answer to these questions is yes when using SHR w/1 disk redundancy, but I'm unclear how 2 disk redundancy factors in.

[HarryPotter]

1) yes
2) no, you need at least 2(SHR1) or 4(SHR2) 4 TB to get more space than a RAID5 or a RAID6
3) see 2)

There is a RAID calculator: http://www.synology.com/support/RAID_ca ... p?lang=enu

[maxxfi]

There is a RAID calculator: http://www.synology.com/support/RAID_ca ... p?lang=enu

BTW, about the RAID calculator: it shows only what is the storage capacity if all disks are installed at the same time. It does not help those users who wants to know what's the result if they add disk X to their pre-existing array (at least I haven't found a way how to simulate that).

[Captain Awesome]

There is a RAID calculator: http://www.synology.com/support/RAID_ca ... p?lang=enu

BTW, about the RAID calculator: it shows only what is the storage capacity if all disks are installed at the same time. It does not help those users who wants to know what's the result if they add disk X to their pre-existing array (at least I haven't found a way how to simulate that).

I'm not sure I understand what you mean here. Are you speaking specifically about two disk redundancy, a specific RAID type, or all of them?

Using the example I posted earlier, if I start with 2x4TB+2x2TB and later add another 4TB drive to the array, would I not get an additional 4TB in the volume (obviously 4TB minus the overhead and conversion, which means something like 3.7TB or so)?

[maxxfi]

I'm not sure I understand what you mean here. Are you speaking specifically about two disk redundancy, a specific RAID type, or all of them?

What I mean is that the calculator seems to ignore the limitation (for any form of RAID or SHR) that if e.g. you have an array made with 2TB disks, later you cannot add disks smaller than 2TB.

[Captain Awesome]

I'm not sure I understand what you mean here. Are you speaking specifically about two disk redundancy, a specific RAID type, or all of them?

What I mean is that the calculator seems to ignore the limitation (for any form of RAID or SHR) that if e.g. you have an array made with 2TB disks, later you cannot add disks smaller than 2TB.

Ah, I understand now. Thanks!