Recommendation SSD (cache drive)

[coolspot]

Anyone have a recommendation for a Cache drive? My EVO 840 seems to have died and I'm considering either 2 x Crucial MX500s or 2 x WD10JFC (2.5" WD Reds).

 

Any other options I should look at?

 

I'm thinking of avoiding Samsung because it has  bad warranty service in Canada (near non-existent).

 

Thanks.

[NewDisplayName]

Just one little tip, dont trust manufactures who make "PRO" and "RED" and "ENTERPRISE" SSDs/HDDs.

 

There is no noticeable difference between them.

Backplaze is the only company i know (https://www.backblaze.com/blog/hard-drive-stats-for-2017/ | https://www.backblaze.com/blog/hard-drive-stats-for-q1-2018/ ) which reports hdd failures, they advise to NOT USE special hdds/sdds because there is not nitceable difference.

 

Save the money (!)

 

For myself i use 2

Samsung_SSD_850_EVO_500GB

since ~3 years without problems 24/7.

The time where price make a difference is over. 

 

Wear Level count it says 95, so i guess (https://superuser.com/questions/1037644/samsung-ssd-wear-leveling-count-meaning) i only used 5% till now. Im happy.

 

I might be wrong, but i never seen any data (execpt from manufactures) who prove any noticeable difference, exept the price.

 

Quote

 

But the report points out that hard drives manufactured specifically for enterprise use aren’t any more reliable than drives sold on the mainstream market. The observation is based on the company’s use of 8TB hard drives manufactured by Seagate: Model ST8000NM0055 for data centers, and model ST8000DM002 for the mainstream desktop market.

The company reports that the enterprise-focused model has an annualized failure rate of 1.2 percent whereas the mainstream model has an annualized failure rate of 1.1 percent. As the numbers show, the failure rates are very similar, meaning the enterprise model isn’t any more reliable than its mainstream sibling despite the former’s “premium” price tag. Still, there are benefits in using the premium enterprise-based storage solution.
 

 

Edited June 20, 2018 by nuhll

[coolspot]

I ended up getting two Intel 525S SSDs. These drives are pretty cheap, have a 5-year warranty, and are very durable - 144TBW for the 250GB model which is on par with the Evo 860 (150TBW) and much better than the Crucial MX500 (100TBW).

Edited June 23, 2018 by coolspot

[NewDisplayName]

850 evo has up to 300 TBW and would be probably cheaper

https://www.samsung.com/semiconductor/minisite/ssd/product/consumer/850evo/

Edited June 23, 2018 by nuhll

[coolspot]

3 minutes ago, nuhll said:

850 evo has up to 300 TBW and would be probably cheaper

https://www.samsung.com/semiconductor/minisite/ssd/product/consumer/850evo/

 

You have to read the fine print ... 300TBW is on the 2/4TB models which is pretty bad for a drive of that size. The 250GB model only has 75TBW for the EVO 850.

 

EVO 860 on the otherhand has like 2.4PBW for the 4TB models and 150TBW for the 250GB model.

 

The Intel 525S and EVO 860 have the best endurance and warranty for consumer drives as far as I'm aware of at the moment. I ruled out Samsung because they only sell greymarket in Canada - the RMA process is awful here. 

Edited June 23, 2018 by coolspot

[NewDisplayName]

thats why i said up to. did you take the 250gb model? i guessed u took atleast 500gb.

[coolspot]

Just now, nuhll said:

thats why i said up to. did you take the 250gb model? i guessed u took atleast 500gb.

 

I got the 250GB Intel 545S, it has 144TBW. 

[NewDisplayName]

ah, okay, i have 500 and im at the point that i rather have got the 1tb modell

[binhex]

ah, okay, i have 500 and im at the point that i rather have got the 1tb modell

500GB 860 Evo for me, tbw of 300 is enough for my needs.

Sent from my SM-G935F using Tapatalk

[NewDisplayName]

yeah just good price/what you get

[Snuups]

Is there a way to use the Cache as it would if it were a cache?

 

My Problem: when cache is full errors occurs. That is not acceptable. Even installing a cache bigger than what I can write in one hour does not solve the Problem. 

 

I expect a cache to work like a cache. totally transparent. Like the Data start to write immediately to the disks. If cache is full data will still flow but slower. No error in any circumstance.

[JonathanM]

30 minutes ago, Snuups said:

Is there a way to use the Cache as it would if it were a cache?

 

My Problem: when cache is full errors occurs. That is not acceptable. Even installing a cache bigger than what I can write in one hour does not solve the Problem. 

 

I expect a cache to work like a cache. totally transparent. Like the Data start to write immediately to the disks. If cache is full data will still flow but slower. No error in any circumstance.

You need to set your minimum free for the cache drive to be larger than the biggest single file you plan to write.

[trurl]

1 hour ago, Snuups said:

Is there a way to use the Cache as it would if it were a cache?

 

My Problem: when cache is full errors occurs. That is not acceptable. Even installing a cache bigger than what I can write in one hour does not solve the Problem. 

 

I expect a cache to work like a cache. totally transparent. Like the Data start to write immediately to the disks. If cache is full data will still flow but slower. No error in any circumstance.

It is impossible to move data from fast SSD cache to the slower HDD parity array as fast as you can write to fast SSD cache, no matter how large your cache is. You just need to reconsider how you are using cache.

 

First of all, don't cache the initial data load. Cache only gets in the way because

Quote

It is impossible to move data from fast SSD cache to the slower HDD parity array as fast as you can write to fast SSD cache, no matter how large your cache is.

Some people even do the initial data load without parity since parity slows down writes.

 

After the initial data load, consider whether you really need fast writing to some of your shares. Many of the writes to my server are from unattended processes. Since I am not sitting there waiting for them to complete, no need to cache them.

 

Finally, mover is intended to run during idle time because

Quote

It is impossible to move data from fast SSD cache to the slower HDD parity array as fast as you can write to fast SSD cache, no matter how large your cache is.

Instead of being concerned with how much you can write in an hour, it would really be better to consider how much you might write to cache (and how much you might instead write directly to the array) during the day so it can be moved to the array at night when you aren't writing new files to cache.

 

If you want more specific advice on how to avoid filling cache, post your Diagnostics. Tools - Diagnostics, attach complete Diagnostics ZIP file to your NEXT post in this thread.

[Snuups]

Thank you (both) for the advice. I copy large files and may files to my unRAID server. Like 8 TB in a single copy. My unRAID has 2 Parity disks and encryption on. My speed is around 50 MB/s. So a SSD cache might not do the trick at all.

I thought using 1 TB SDD cache might be faster because it writes to the disks even when no operation is active. What does not work because i mostly copy larger chunks than a cache drive can be. I guess I have to live with the speed I can get with no cache. My hope was a setting that the cache will be fast as long as the cache ist not full and reduce speed when it is full. Like caches normally work. And of cause writing to the disks immediately after data arrives. Like an instant (I don't know the term unRAID uses für moving the files to the drives) working all the time.

Edited August 18, 2020 by Snuups

[trurl]

5 hours ago, jonathanm said:

You need to set your minimum free for the cache drive to be larger than the biggest single file you plan to write.

The point of this is that for cache-yes or cache-prefer shares, when cache gets too full (less than Minimum remaining as set in Global Share Settings), it automatically switches to writing to the array instead.

 

[Snuups]

So if I set a 1 TB cache to minimum free of 0.95 TB it will clear the cache immediately and when the cache is full it will not make an error?

[ChatNoir]

 

2 hours ago, Snuups said:

So if I set a 1 TB cache to minimum free of 0.95 TB it will clear the cache immediately and when the cache is full it will not make an error?

From what I understand, with such a setup, unraid will skip the cache and directly write to the array. You might not have an error, but you would never use your SSD for cache.

[Snuups]

OK, I understand.

 

In this case cache is just something I can't use at all. No problem.