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April 25th, 2018 07:00
3.84 MLC vs TLC disks
Currently we have a two tier SC system (TLC in tier 1, and 7k disks in Tier 3). . the tier 1 TLC SSD are all the 3.84TB variety. . If we want to add a few more to tier 1 - would adding the Dell/Compellent 3.84tb MLC be considered the same class as the existing 3.84 TLC ssd's ? or would it create a new tier with the drives and require 6+ ? Hoping that it can accept the Dell/Compellent MLC and TLC drives as the same "Read Intensive" SSD drive for the same tier.
Also as a quick question - there isn't a point to create a new MLC tier, but can anyone provide some feedback as to whether having a smaller SLC WI SSD give better write performance ? We dont have a need for heavy writes that necessitates getting WI drives, but I know before the WI/SLC drives had better write performance, but not sure that is worth the additional tier to manage.
Thanks
DELL-Sam L
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April 25th, 2018 11:00
Hello edfang,
If you were to add more SSD & they are not 100% identical then a new Tier would be created. Also, when you add new RI or WI disk they need to be added in a bank of 6 at a time.
As you stated you don’t have heavy writes then getting more RI drives would be better. If your writes are below 150mbs then I wouldn’t see a need at getting RI drives. Here is a screen shot of how to check your drives to see how much they are being accessed.
Please let us know if you have any other questions.
1 Attachment
WI disk.png
edfang
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April 25th, 2018 12:00
Gotcha. . that was what I thought might happen with the slightly different drive type. . And yes, understand the 6+ configuration that would be required. .
Your SM display looks a bit different than mine but the data is relatively at the same place. Your shows Summary/Storage/Hardware/IO Usage/Charting/Alerts/Logs
whereas mine has the exact same but missing IO Usage. But that same charge is under the charting and disks. .
But you mention 150mb/sec. . Thats what we are coming up against. . While we dont have heavy writes in the sense of DWPD and fatiguing the SSD prematurely. .. we do run a steady mb/sec and sometimes thats around 30-50. but we want the writes to be as fast as possible at times, including for snapshot or bulk moves of data. . We figured the write transfers would be faster than 150mb/sec. . is that the limit on these RI ssd disks ? Is their a method to get faster throughput on writes than 150mb/sec ? we're seeing about 120mb/sec of so, which makes your mention of 150 exactly what we're seeing. . That was the question was whether if we put 8 400/800gb WI disks . .which presumable would create a new T1. . would that increase the write throughput fairly dramatically ? like maybe to 200-300mb/sec ?