SHR in DSM 2.3 - detailed description discussion thread

[Alfredo]

If I use SHR to create regular RAID-5 arrays (4*1TB for example), will I still experience 10% less performance? Or is that only true for hybrid RAID arrays?

[almograve]

3. Volume creation speed is a variable, dependent on the disks used, and the performance of the DiskStation. As an example, using 5xST31000528AS in a DS1010+, firmware 1045, with complete consistency check for me took about 5 hours to build a volume.

Hope this helps.

FYI
Took me 6hours on the 410j with 3x750 and 1x1,5 to.

I'm copying the data back to the NAS directly attached to my laptop via Ethernet and I'm getting 21/22mo/s "upload".

Thank you,
almo

[almograve]

On a scale of 1 to 10 how much would give to having a UPS when using SHR? Knowing that in a year in my appartement I've never experience a shortage that I could notice of.

I would always recommend using a UPS, regardless of what type of RAID you use. For me, spending a couple hundred dollars on a UPS already saved my data from damage loss during a snow storm and the ensuing main power stability errors. Data is more valuable than a couple hundred dollars.

Thank you, you are right, I might be trying to save money where I shoudn't....
I'll go for a 600VA MGE at 115 dollars in France.

[smills]

Just got my DS409 and installed 3 x 2TB drives (plan to install a 4th soon).

Should I use SHR or RAID 5 ?

From what I read SHR is 10-15% slower than RAID 5 ? IS that correct?

[Hi-Jack]

In your case use RAID5. SHR is only usefull when using different size disks and remains a software based solution which is responsible for the slightly less performance it offers... In my opinion SHR is only usefull if having different sized hard drives above 1TB (1.0, 1.5 and 2.0TB) as otherwise the investment in a 4-BAY or 5-BAY server is over the top.

So SHR is only good under certain conditions...
Don't use it if you ahve the right conditions to use regular RAID5 or 6...

[almograve]

In your case use RAID5. SHR is only usefull when using different size disks and remains a software based solution which is responsible for the slightly less performance it offers... In my opinion SHR is only usefull if having different sized hard drives above 1TB (1.0, 1.5 and 2.0TB) as otherwise the investment in a 4-BAY or 5-BAY server is over the top.

So SHR is only good under certain conditions...
Don't use it if you ahve the right conditions to use regular RAID5 or 6...

Are you 100% sure about SHR vs. RAID5? I though that with a configuration of 4x2To the Synology would build a RAID5 anyway! even though you are in "SHR" mode. So it should give the exact same performance. Then, when having different HDD sizes, the mix would build a through SHR and then lower the performances...

[enestu]

If I use SHR to create regular RAID-5 arrays (4*1TB for example), will I still experience 10% less performance? Or is that only true for hybrid RAID arrays?

Hi from France,
Sorry for my poor english :
- Dear Franklin this question from is for lot of user The Question: for a typical 5* or 4* Fixed size HDD with a strong nas (409+,410 minimum) is there a significant loss of performance ?
- Having serious benchmark about SHR wich is the main feature of DSM2.3 is really important for customers or buyers (It should be done before press marketing)
- Is there a risk in case of emergency/recovery versus Raid5 (I think but I'm not omniscient that the reliability/security of raid5 is the main raison to acquire a NAS) ?

In my case, I purchase new 410 with a typical 3*1.5To and Raid 5 is perfect but If in 1-2years, I could slowly (buying 1 by 1 and adding it) expand my NAS with 3TB disk, It's could be the good choice to setup SHR...
Thanks

[enestu]

Hi,
Another question:
If I have a 4 bay NAS full with 4*1TB in SHR, Is it possible to change 1 HDD (or two) to 2TB and gain space (I change one drive, let reconstruct and after change another, let reconstruct and gain 1TB) ?

Thanks

[bigbearangus]

I have a question. I just ordered a disk station DS410, and my hard drive gona be 2TB, 2TB, 1.5TB, 1TB,
1. So under SHR, what is the maximum drive space will my volume be? Is there a web page can auto calculate for me?
2. One of the 2TB I have is WD WD15EADS which on your web site says it's unreliable and not recommended. So what is the best way to protect my data in case of a that 2TB hard drive failure? Raid 5 or SHR? or any other raid configuration?

Thanks
Angus

[bigbearangus]

I calculated myself, total space I would get is 6 TB total useable space, 0.5 TB will be wasted. but I'm still not sure which one is better in term of performance and realiablity over raid 5 or SHR.
Angus

[chum]

Based on my calculations, using SHR you would have 4.5TB of useable space.

The recommendation is by starting with smaller drives first when using SHR.

example;

1TB = 1TB Basic
1TB + 1.5TB = 1TB RAID1 (500GB wasted)
1TB + 1.5TB + 2TB = 2TB RAID5 + 500GB RAID1 (500GB wasted)
1TB + 1.5TB + 2TB + 2TB = 3TB RAID5 + 1TB RAID5 + 500GB RAID1 (no wastage) total useable space 4.5TB

As far as performance is concerned, a 10-15% performance loss would be incurred when using SHR. Although I have had no experience personally with SHR, I would avoid using SHR on any of the lower end models (j models) unless absolutely necessary.

If you weren't using SHR, you could create a 3TB (useable) RAID5 volume with 2.5TB of wasted space. (this is based on your above mentioned drive sizes 1TB+1.5TB+2TB+2TB)
You could also create 2 volumes without using SHR and have a total useable space of 3TB by creating two RAID1 volumes. Either way when not using SHR and ensuring all of your data has some form of redundancy you can only have 3TB of useable space based on your drive sizes.

If you want to make use of that wasted space, either use SHR from the start and take the performance hit, or sacrifice redundancy and create separate volumes and don't use SHR.

Hope this helps.

[bigbearangus]

I finally merged all drive to the SHR in DSM 2.3, but actually I only got 3.5 TB of useable space, perhaps it's due to the 2 TB actually is 1.8TB and 1.5 TB actually is 1.3 TB. 1TB actually is 0.9 TB.

Based on my calculations, using SHR you would have 4.5TB of useable space.

The recommendation is by starting with smaller drives first when using SHR.

example;

1TB = 1TB Basic
1TB + 1.5TB = 1TB RAID1 (500GB wasted)
1TB + 1.5TB + 2TB = 2TB RAID5 + 500GB RAID1 (500GB wasted)
1TB + 1.5TB + 2TB + 2TB = 3TB RAID5 + 1TB RAID5 + 500GB RAID1 (no wastage) total useable space 4.5TB

As far as performance is concerned, a 10-15% performance loss would be incurred when using SHR. Although I have had no experience personally with SHR, I would avoid using SHR on any of the lower end models (j models) unless absolutely necessary.

If you weren't using SHR, you could create a 3TB (useable) RAID5 volume with 2.5TB of wasted space. (this is based on your above mentioned drive sizes 1TB+1.5TB+2TB+2TB)
You could also create 2 volumes without using SHR and have a total useable space of 3TB by creating two RAID1 volumes. Either way when not using SHR and ensuring all of your data has some form of redundancy you can only have 3TB of useable space based on your drive sizes.

If you want to make use of that wasted space, either use SHR from the start and take the performance hit, or sacrifice redundancy and create separate volumes and don't use SHR.

Hope this helps.

[Kbern]

Hi. I am trying to decide if I should purchase a qnap ts-419p or synology 410.

Wrt shr performance, it seems like the most important question, which has been asked repeatedly, is never answered, which is:
"If I use SHR to create regular RAID-5 arrays (4*1TB for example), will I still experience 10% less performance? Or is that only true for hybrid RAID arrays?"

It's a key question because doing so means (in the above example) I might have no performance hit the whole time all my drives are the same (maybe a year) then a 10% hit during the 6 months it would take me to upgrade them all to (eg) 2tb, and then back to no performance hit once they are all 2tb.

Franklin? Anyone?

Thanks!