QNAP NAS Community Forum

Hello

I'm new to this and cant find a definitive answer to this question, would i be better off using SSD's for OS / System volume or read/write Cache.

what setup would give better day to day performance,

TVS-882
5x6TB Raid 6
2x512GB SSD Raid 1
1gbE LAN

This server is intended for
PLex
1 or 2 VM's
General file storage

You can't find a definitive answer because it doesn't exist.

I was in the same spot as you with two 512 GB SSDs. I thought that if the SSDs are used for caching they're dedicated for that and can't be used as storage.

Therefore I used the SSDs in RAID 1 for the OS. Not because it's very important to have the OS on SSDs (it isn't) but the VM-files can be placed there as well and that will make a big difference for VM-performance. Be careful to not fill them up completely though.

If I ever think I need a SSD cache I can always easily add that later.

With a gigabit LAN, that'll be your performance bottleneck for the networked clients not the disks.

10gbe guide suggests using ssd caching to help achieve the 10gbe speeds that your hdds (non ssds basically) array can benefit from
https://blog.qnap.com/10gbe-walkthrough-en/


also as previously mentioned, the ssd is good for vm and apps.

for qts and installed qpkg app, ssd can improve latency and can definitely fit on the tight space of ssds 512gb, 1tb, 2tb.

for a long while i used ssd raid1 as caching, assuming it can help improve qts responsiveness. But i'm not sure that it did tbh. So this time around, i instead install qts and the qpkg apps directly on the ssd, and not use it as a ssd cache. This will certainly help with responsiveness of the apps as they are on a ssd directly.

my main nas does not have 10gbe to begin with

spike had some interesting usage case info. He mentions how he burned through his ssd cache after a couple of months (think he said 6 ish?). I have no idea how he setup his cache settings or what kind of typical usage he does. I assume he set to cache everything, and did a ton of transfers very frequently. Also doesn't help if your SSD tbw/endurance is not rated well. Seagate is marketing a SSD for NAS which supposedly has much better endurance meant for a NAS.


I looked at what trexx does, and he suggested setting the SSD raid1 as a static volume for best performance. Not setting it up in pool thick volume, won't let you use snapshots for that raid array however if you do that fyi. I do however have my hdd 4x4tb raid5 array in thick vol/pool which does have snapshots working however.


there is another alternative to ssd cache acceleration which is qtier. but that would require (highly recommended) using a UPS, since it does both read and write as default settings. Not much experience with this ssd setup, best ask others what benefit it has.


ideally you would go for 1tb ssd. but maybe 500gb ssd will be fine as bare minimum. but these days i don't recommend 250gb capacities (too little space to do much with it, also prices for 500gb ssds is pretty reasonable).

Here was an interesting point as to why add QTS onto the SSD

Vortax_Wyvern

Yes, it will.

Most of background work is performed by system pool, since constant read/writes are needed.

If you set a SSD RAID array as system volumen, your NAS will be less noisy.

Source: I did it myself.

https://www.reddit.com/r/qnap/comments/ ... ng_on_ssd/


but i think his setup uses hdd sleep mode to put the inactive hdds to sleep though for it to work like that? because my own setup is with hdd sleep disable, so hdds are running 24/7

Moogle Stiltzkin wrote: ↑Mon Aug 26, 2019 6:52 am but i think his setup uses hdd sleep mode to put the inactive hdds to sleep though for it to work like that?

Unless Qnap have done a major system design change lately, disk spindown is done across all disks. So any disk activity on any disk (for example an SSD) will wake all disks (also the mechanical) up.

Also, the hidden system partitions are in a multi-disk RAID 1 across ALL disks in the system. So any write there will write to ALL disks.

P3R wrote:

Moogle Stiltzkin wrote: ↑Mon Aug 26, 2019 6:52 am but i think his setup uses hdd sleep mode to put the inactive hdds to sleep though for it to work like that?

Unless Qnap have done a major system design change lately, disk spindown is done across all disks. So any disk activity on any disk (for example an SSD) will wake all disks (also the mechanical) up.

Also, the hidden system partitions are in a multi-disk RAID 1 across ALL disks in the system. So any write there will write to ALL disks.

Yes this is correct, I've talked with qnap about this very thing, and unfortunately, if 1 disc is in use/awake, then every other disk will be awake.

Which is ashame it works as such, as in my situation, I may need a raid set in use 24/7, but the other sets with 30+ hddz don't need to spinning all that often.

Thanks for the comments.

Think ill use SSD for OS / APP's. M.2 Cache can always be added if it upgrade to a 10gbe later.

Moogle Stiltzkin wrote: ↑Mon Aug 26, 2019 4:31 am
there is another alternative to ssd cache acceleration which is qtier. but that would require (highly recommended) using a UPS, since it does both read and write as default settings. Not much experience with this ssd setup, best ask others what benefit it has.

i did look into this couldn't find any info about a mixed raid qtier setup, 2xSSD's and a raid 6 HDD would only be as reliable as the RAID 1 SSD's. could be wrong but Im guessing this based on mixed raid in a storage pool losing one raid is complete data loss.

mr.porter wrote: ↑Mon Aug 26, 2019 3:59 pm i did look into this couldn't find any info about a mixed raid qtier setup, 2xSSD's and a raid 6 HDD would only be as reliable as the RAID 1 SSD's.

Yes.

https://www.qnap.com/solution/qtier-auto-tiering/en/
https://www.qnap.com/en/how-to/tutorial ... erformance

I think very few use Qtier, at least it's almost never discussed here except for occasionally being promoted by people that don't use it.

I can't remember any experienced administrator being enthusiastic or even positive about Qtier. The main problem is that you lose control over where your data is located. The storage become a black box with unknown function.

I use qtier

works great so far...my vms got way snappier as (I assume) the SSD images were moved up to the faster tier

you can specify to only tier up certain shares(e.g. containers or vm shares) ...I have it setup for all shares for now

I stand corrected, there is one.

And he even sound enthusiastic about it.

well .. it is very black box..so if you are ok to trust that one try it (I have multiple backups at all times)

I have used QTier before with my smaller M.2's and it was ok. Not sure if I noticed alot of benefit or not as I had my VM's on separate SSD Raid-1 config. One thing that is nice with the new 4.4.x beta is that you can UN-INSTALL Qtier if you don't like it (which previously meant rebuilding your NAS).

I currently have some 1TB m.2's as caching for my HDD's and do notice a major speed improvement when backing up my VM"s from SSD onto HDD for the backup.

Never tier with small SSDs, IO will move backwards and forwards between SSDs and HDDs as there is probably not enough space.

storageman wrote:Never tier with small SSDs, IO will move backwards and forwards between SSDs and HDDs as there is probably not enough space.

Smaller were 525GB ssds so wasn’t too small.


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P3R wrote: ↑Mon Aug 26, 2019 2:27 pm

Moogle Stiltzkin wrote: ↑Mon Aug 26, 2019 6:52 am but i think his setup uses hdd sleep mode to put the inactive hdds to sleep though for it to work like that?

Unless Qnap have done a major system design change lately, disk spindown is done across all disks. So any disk activity on any disk (for example an SSD) will wake all disks (also the mechanical) up.

Also, the hidden system partitions are in a multi-disk RAID 1 across ALL disks in the system. So any write there will write to ALL disks.

Can Qtier help somehow? I would really love to have one SSD fully dedicated to OS, and cheap HDD for data solely. I would love to make sure that hdd are idle as much as possible, but your statement puts me off. I guess there is no way to achieve that right?