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NAS - cache on HDD - More, or Less?

Posted: Tue Feb 02, 2021 12:41 pm
by Neto
I'm attempting to evaluate the relative advantages vs dangers of using NAS HDDs with a higher level of cache. From what I read on a wiki article about buffering on HDDs, it sounds like a double edged sword. Higher cache means the data write process is smoother & more quickly frees the computer for other tasks, but can reduce data quality, especially if the operator continues to send new read/write 'jobs' to the NAS (and of course if power drops to the NAS before it has written data from the cache to the physical platter).

The price difference going from 64 to 256 is not that much, but from 256 to 512 it leaps wildly.

Anyone have experiences they can share with me on this question?

Re: NAS - cache on HDD - More, or Less?

Posted: Wed Feb 03, 2021 12:10 am
by nett
Neto wrote:I'm attempting to evaluate the relative advantages vs dangers of using NAS HDDs with a higher level of cache. From what I read on a wiki article about buffering on HDDs, it sounds like a double edged sword. Higher cache means the data write process is smoother & more quickly frees the computer for other tasks, but can reduce data quality, especially if the operator continues to send new read/write 'jobs' to the NAS (and of course if power drops to the NAS before it has written data from the cache to the physical platter).

The price difference going from 64 to 256 is not that much, but from 256 to 512 it leaps wildly.

Anyone have experiences they can share with me on this question?
Depends on what your use case is?

for instance, if you're streaming 4k video, or trying to run VMs with storage targeting the NAS, I would go for more cache. If you're primarily going to be backing up important files, then as you said, less cache is slightly more reliable.

Re: NAS - cache on HDD - More, or Less?

Posted: Wed Feb 03, 2021 7:00 am
by Neto
nett wrote:
Neto wrote:I'm attempting to evaluate the relative advantages vs dangers of using NAS HDDs with a higher level of cache. From what I read on a wiki article about buffering on HDDs, it sounds like a double edged sword. Higher cache means the data write process is smoother & more quickly frees the computer for other tasks, but can reduce data quality, especially if the operator continues to send new read/write 'jobs' to the NAS (and of course if power drops to the NAS before it has written data from the cache to the physical platter).

The price difference going from 64 to 256 is not that much, but from 256 to 512 it leaps wildly.

Anyone have experiences they can share with me on this question?
Depends on what your use case is?

for instance, if you're streaming 4k video, or trying to run VMs with storage targeting the NAS, I would go for more cache. If you're primarily going to be backing up important files, then as you said, less cache is slightly more reliable.
It is for a business with 9 work stations on a gigabit peer-to-peer network, storing and backing up QuickBooks company files and QB Attachments folder contents, and perhaps mainly CAD drawings.

Re: NAS - cache on HDD - More, or Less?

Posted: Wed Feb 03, 2021 10:11 am
by nett
Neto wrote:
nett wrote:
Neto wrote:I'm attempting to evaluate the relative advantages vs dangers of using NAS HDDs with a higher level of cache. From what I read on a wiki article about buffering on HDDs, it sounds like a double edged sword. Higher cache means the data write process is smoother & more quickly frees the computer for other tasks, but can reduce data quality, especially if the operator continues to send new read/write 'jobs' to the NAS (and of course if power drops to the NAS before it has written data from the cache to the physical platter).

The price difference going from 64 to 256 is not that much, but from 256 to 512 it leaps wildly.

Anyone have experiences they can share with me on this question?
Depends on what your use case is?

for instance, if you're streaming 4k video, or trying to run VMs with storage targeting the NAS, I would go for more cache. If you're primarily going to be backing up important files, then as you said, less cache is slightly more reliable.
It is for a business with 9 work stations on a gigabit peer-to-peer network, storing and backing up QuickBooks company files and QB Attachments folder contents, and perhaps mainly CAD drawings.
I would go with more redundancy / reliability in that case. It makes more sense to put money towards an extra drive or controller, than towards the negligible performance boost from more cache

Re: NAS - cache on HDD - More, or Less?

Posted: Wed Feb 03, 2021 12:55 pm
by Neto
nett wrote:
Neto wrote:
nett wrote:
Depends on what your use case is?

for instance, if you're streaming 4k video, or trying to run VMs with storage targeting the NAS, I would go for more cache. If you're primarily going to be backing up important files, then as you said, less cache is slightly more reliable.
It is for a business with 9 work stations on a gigabit peer-to-peer network, storing and backing up QuickBooks company files and QB Attachments folder contents, and perhaps mainly CAD drawings.
I would go with more redundancy / reliability in that case. It makes more sense to put money towards an extra drive or controller, than towards the negligible performance boost from more cache
Thanks. The customer messaged me this morning to go with the 256 cache, so I have already ordered 2 of those. (These drives are to replace 5 year old HDDs in a dual drive IOSafe. They will be adding more NAS devices later.)

What are the advantages of a rack NAS?
From what I've seen so far:
Redundant PSUs.
Ability to add modules for more drives.

Anything else?