What is Cache Acceleration? Will it benefit me?

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elee532
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What is Cache Acceleration? Will it benefit me?

Postby elee532 » Sat Feb 20, 2016 11:17 pm

Can someone explain in basic terms what Cache Acceleration is on the TS-653A? I currently have a 64gb SSD drive lying around, and an extra bay in my NAS. I'm using the NAS mostly as a media storage and player device (Kodi and JRiver via HDMI to my TV) for 5.1 flac files, Blu-rays, and SACD ISOs. I currently have a single RAID 5 using 3 HGST 6tb 7200rpm drives.

Is this the kind of thing that cache acceleration would benefit from. If so, any guidelines for setting it up?

Thanks!

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Re: What is Cache Acceleration? Will it benefit me?

Postby Don » Sun Feb 21, 2016 12:14 am

Have your searched the forum (97 hits) or read the manual?
ADVICE - read the manual (online) and use the forum search feature (upper right hand corner) before posting.
Chances are very good you will find your answer.


It is a recommended to use RAID. It is also recommended to have external backups. RAID is designed to protect you from disk failure and keep your system running and data accessible while the disk is replaced and the RAID rebuilt. Backups will allow you to recover data that is lost or corrupted, or from catastrophic system failure. One does not replace the other.

Bugs and feature requests need to be submitted to QNAP via their helpdesk.

Online Manuals
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Re: What is Cache Acceleration? Will it benefit me?

Postby elee532 » Sun Feb 21, 2016 12:41 am

Yes, I have done both.

The manual give some very basic instructions for configuring the Cache Acceleration settings. However, it doesn't explain (at least in a way that a newbie would understand) WHAT cache acceleration is, and what the benefits are in using it. What kind/size of SSD is needed? Will it have any benefit in my particular usage scenario?

I guess I'm looking for something like "Cache Acceleration 101." When I searched the forum, nothing seemed to quite answer my questions either.

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Re: What is Cache Acceleration? Will it benefit me?

Postby elee532 » Sun Feb 21, 2016 11:41 pm

A few more questions:

I have two SSD drives lying around. One is 80GB@ 3Gb/s the other is 128GB at 6Gb/s. Should I use both, or just one?

Should I use the Read Only or the Read/Write option?

What setting should I use for "Bypass Block Size?" None seems to be the default?

As I mentioned above, I'm using the NAS primarily as storage and playback device for hi-rez music and video.

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Re: What is Cache Acceleration? Will it benefit me?

Postby P3R » Mon Feb 22, 2016 7:57 am

A cache in general is having a faster media (in this case SSD) that keeps a subset of the data on a slower media (in this case HDD) with the intention of speeding access to that data up.

A cache is beneficial:
In busy systems, if the slower media is a bottleneck.
When a subset of the data is accessed repetedly.
When smaller chunks of data is accessed randomly.

A cache is not (or at least less) beneficial:
When the slower media isn't a bottleneck.
When large chunks of data is accessed sequentially.

Judging by the description of how you use the NAS, I doubt using a cache will have any positive effects. When streaming hi-res material, a cache may actually affect performance negatively as populating the cache with data that isn't being accessed again any time soon is a wasted effort.
RAID have never ever been a replacement for backups. Without backups on a different system (preferably placed at another site), you will eventually lose data!

A non-RAID configuration (including RAID 0, which isn't really RAID) with a backup on a separate media protects your data far better than any RAID-volume without backup.

All data storage consists of both the primary storage and the backups. It's your money and your data, spend the storage budget wisely or pay with your data!

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Re: What is Cache Acceleration? Will it benefit me?

Postby tinyark » Wed Jan 18, 2017 11:01 pm

Hi there,

I'm in a similar boat and debating wether to buy the QNAP 871T (No cache acceleration) or the TVS-1282T.

Up to 8 users will be editing 4K footage over our network and just wondering if TVS-1282T will be beneficial for our company.

Also will increased size SSD'S for caching benefit us also?

Many Thanks,

Alex

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Re: What is Cache Acceleration? Will it benefit me?

Postby Bob Zelin » Thu Jan 19, 2017 7:54 am

Hi -
eight editors, all editing in 4K -
you are talking about around 90MB/sec per client with a single stream of video. You need a faster RAID array, like the TVS-EC1680U-SAS-RP-R2 with a 10G switch.
IF you were doing 8 users with 1080i ProRes editing (20 - 30 MB/sec), then no issue, but with 4K, you are pushing what 8 drives can do - with or without the 4 SSD cache.

People say "well, what if I get brand X or brand Y, will that work ?". It's all about what the total bandwidth of the drives will do. I don't care who makes it -
you can't get eight 7200 RPM drives to do 1600 MB/sec total bandwidth. If you have 2 - 3 serious editors, and the rest of the 8 are just screening (like producers) then you
can get away with it, but with 8 heavy duty 4K jobs going on, you are not making this happen with an 871T or 1282T. Cache or no cache.

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Re: What is Cache Acceleration? Will it benefit me?

Postby razormoon » Thu Jan 19, 2017 9:30 am

tinyark wrote:Hi there,

I'm in a similar boat and debating wether to buy the QNAP 871T (No cache acceleration) or the TVS-1282T.

Up to 8 users will be editing 4K footage over our network and just wondering if TVS-1282T will be beneficial for our company.

Also will increased size SSD'S for caching benefit us also?

Many Thanks,

Alex


Indeed you'll need so high speed nics and at the very least, get a thunderbolt model which are made with video editing in mind.

As far as cache, I've set mine to 2mb and everything runs smoothly with SSD as cache. It's good because it speeds up my VMs as well.
Anything above 2mb will give you slow results when you first run an app or VM as it needs to load the data. All subsequent actions will be faster.
That being said...anything above 2mb will be mostly for large loads like database or video playback so it won't necessarily improve things especially with smaller ssd.

It does make a big difference for everyday use, especially when you're running VMs.
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Re: What is Cache Acceleration? Will it benefit me?

Postby Bob Zelin » Thu Jan 19, 2017 9:17 pm

these are the 10G thunderbolt NIC's that I recommend -
Sonnet Twin 10G
Promise SanLink2
ATTO ThunderLink (like the NT2102)
I do not recommend the Akitio, as it is buss powered, and over heats and dies after 8 hours of continuous use.

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Re: What is Cache Acceleration? Will it benefit me?

Postby tinyark » Thu Jan 19, 2017 10:13 pm

Thanks Bob,

Iv'e read a couple of bad reviews on the Promise Sanlink2 so was going to opt for the Sonnet TWIN10G.

Would you agree or is the Sanlink just as good(it's a little cheaper!)?

Cheers,

Alex

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Re: What is Cache Acceleration? Will it benefit me?

Postby Bob Zelin » Fri Jan 20, 2017 7:49 am

I only use the Twin 10G now. They are great. But I don't know what bad reviews you have seen on the Promise SanLink2
It works as well. In the US, the Twin10G is cheaper.

Bob
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Re: What is Cache Acceleration? Will it benefit me?

Postby dialbat » Tue Feb 07, 2017 6:23 pm

Can i bulch in with my question? :)
I have TS-470Pro, with 4 Seagate ST3000VN0001-1SF176 SATA drives, all in RAID5.
I have Windows Server 2012 R2 running on virtual machine and iSCSI disks, all mapped from same Storage pool.
10 users that do CAD work of the server on project files. File History backups that save to the same Server.
All was good, but in past month it became quite slow in creating folders and working on project files.
I'm thinking of adding SSD for cache acceleration.
Would that help?

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Re: What is Cache Acceleration? Will it benefit me?

Postby robertkrz » Thu Mar 23, 2017 9:44 pm

What about if SSD cache of system disk (HDD) will be setup where all applications are installed?
Will it cache also applications or only other data stored in shares?

Or is it better idea to just setup SSD as system disk?

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Re: What is Cache Acceleration? Will it benefit me?

Postby teckel » Sat May 20, 2017 12:37 am

Using two SSDs for read-write cache acceleration is the way to go. This creates a RAID1 cache array. I have mine setup to cache all, with a bypass block size of none. I purchased two Samsung 850 EVO 250GB drives for the task. I use my NAS mainly for entertainment, file sharing, virtualization, and security camera.

Since installing the SSD cache acceleration, the NAS is super quiet. Before, it had to constantly write security camera streams, read/write file shares, and I almost always have at least one virtualization running. Now it seems to read/write mostly to/from the SSD cache. Also, virtualization is MUCH faster. Boot times and running it in general is SUPER snappy.

One would probably never notice a speed difference for watching videos, file sharing, or the security cameras. But, the reduced reading/writing to the platter drives is still a benefit from reduced noise (and probably wear and tear on the platter drives too). I can imagine if I download a video and then watch it within a day (a very common occurrence) the file would be mostly (or all) in the SSD cache as it would take a while to flush through 250GB of cache.

It would be nice if QNAP provided a little more details on what was going on. The Hit Rate History graph is nice, but showing more detail would be welcomed. I think it would help justify the SSD cache to some. Also, I don't get any kind of slow transfer rates that some people have experienced once the cache is 100% allocated. Mine took a couple days to become 100% allocated and I still see a performance gain without any slow-downs.

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Re: What is Cache Acceleration? Will it benefit me?

Postby P3R » Sat May 20, 2017 5:04 am

teckel wrote:Using two SSDs for read-write cache acceleration is the way to go.
This whole thread is a question so leaving your extreme excitement over your own installation aside, do you honestly mean this as advice for the OP here?

Remember that the OP mentioned mainly media consumption as application. No virtualization, no surveillance and not even much of standard office file sharing. Also the question was about a single SSD. I don't think write caching is supported with a single, is it?
Before, it had to constantly write security camera streams, read/write file shares, and I almost always have at least one virtualization running. Now it seems to read/write mostly to/from the SSD cache.
Read caching will in some cases (smaller files accessed more than once) reduce mechanical disk access. Write caching however will not decrease writing to the main storage. All data will eventually be written, it only happens later.

Sequential disk reading and writing makes very little noise, It's the frequent head relocation that happens with random access that's noisy.

I'm guessing that the improvement you experience (and interprets as less writing to mechanical disks) is really that when data is flushed for writing, it's in larger chunks so longer sequential writing. This of course reduces noise so it's an advantage but it doesn't decrease any writing.
But, the reduced reading/writing to the platter drives is still a benefit from reduced noise (and probably wear and tear on the platter drives too).
Disks are designed to read/write, they don't fall apart from doing exactly that.
I think it would help justify the SSD cache to some.
If someone need to justify their purchase after installation I think that's proof that pre-purchase research was inadequate.

Already far too many people buy séxy SSD caching (and ridiculous amounts of RAM) without understanding why, they just think that it's necessary because that's what get attention these days. Ironically most home users are bottlenecked by their networking but still spend money money on making the fast parts of the system faster.

It would be far better if customers first spent their hard earned money on the really important things, like backup and UPSes. That's the basic important stuff necessary if you're looking for a safe data storage, which deep down most users are. At least it looks that way when they come here crying about lost data but have no usable backups.

I may be old fashioned but in my opinion SSD caching should only be considered when a UPS and off-site versioned backups to at least one other independent system in in place.
RAID have never ever been a replacement for backups. Without backups on a different system (preferably placed at another site), you will eventually lose data!

A non-RAID configuration (including RAID 0, which isn't really RAID) with a backup on a separate media protects your data far better than any RAID-volume without backup.

All data storage consists of both the primary storage and the backups. It's your money and your data, spend the storage budget wisely or pay with your data!


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