11-10-2018 07:47 AM
While these drives seem to behave in strict "deterministc read zero after trim" fashion (aka RZAT), like basically any modern ssd. But their firmware for whatever reason doesn't report that bit on those models (nor older variation - determnistic read after trim). This makes it rather frustrating when you plan to for example put those disks behind e.g. low end sas controllers (e.g. LSI 2308 (both it and ir)) that refuse to pass discard if neither RZAT nor DRAT is reported.
This is quite surprising, as older Crucial models reported this just fine (e.g. MX300 or even very old m4).
Please update the firmware to report RZAT correctly.
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11-13-2018 04:12 PM
@msoltyspl sorry about having no timely response. Waiting on someone from engineering to clarify a few things. I should have an answer by tomorrow.
11-14-2018 04:20 PM - edited 11-14-2018 04:22 PM
@msoltyspl I got an answer. Due to the nature of the AES controller and how it handles TRIMed data on the MX500, it is not possible to support RZAT, this is not something that can be addressed by a future firmware update.
11-15-2018 08:52 AM
Thanks for the answer, even as unusual as it sounds.
AES controller ? Unless you mean drive's hardware encryption. The controller is SM2258 - and some other drives using it - e.g. adata's su800 - does report RZAT.
The drive - as far as we could test, doing full write pass and discarding random ranges - behaved like rzat drive would (no self respecting modern ssds behave differently, save perhaps some ultra cheap borderline nonames).
Either way, we will have to look for some other model / brand.
11-15-2018 04:46 PM
Like with all the MX series drives, there is an AES 256bit encryption controller built into the drive that supports hardware encryption. Any data that goes through the SM2258 controller also goes through the AES controller regardless of full disk encryption being setup or not. Once data has been passed through the AES after TRIM has been issued, there is no way to guarantee RZAT implementation on the MX500. While our previous drives may support RZAT, the MX500 with its hardware can not guarantee this.
In any regular consumer environment and even in most enterprise scenarios, RZAT and DRAT simply are not required. This is a consumer grade product which is not advertised for enterprise environments like the unique SAS setup you have. You can certainly look at the Micron enterprise grade SATA drives such as the 5200 and the 5100. They support full implementation of RZAT and are drives that are designed with enterprise setups in mind, and overall would be much better suited for your setup than any consumer grade storage drive.