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P440ar & battery: TRIM not supported w/RAID? Battery-backed write cache in HBA mode?

 
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parnassus
Honored Contributor
Solution

Re: P440ar & battery: TRIM not supported w/RAID? Battery-backed write cache in HBA mode?

The mistery is that the claim is official, at least reading the HPE Smart Array Controllers User Guide (March, 2016) on page 19:

"HBA mode

HPE Smart Array controllers support HBA mode. In HBA mode, all physical drives are presented directly to the operating system and the hardware RAID engine is disabled."

so, the consequence of that sentence is that it should work...or, if it doesn't in your particular case...it probably means that that sentence is not accurate enough (since your SSDs and your OS both support TRIM).

I've the impression that that "HBA mode" role of a Smart Array Controller doesn't act exactly as a real SAS/SATA HBA Card (e.g. like the Avago 9300 family).

An interesting reading could be (it's clearly OT because other brands are invoved but it's interesting because it shed some light on HBA modes role of typical RAID controller cards when the user need to have the most transparent control between the physical disk and the OS, as example when the usage of OpenZFS is planned on a Server) this one...the RAID nature of a Controller Card can be problematic if you look for pure HBA.

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Jimmy Vance
HPE Pro

Re: P440ar & battery: TRIM not supported w/RAID? Battery-backed write cache in HBA mode?

I'll try a P440ar later this afternoon.  I just tried using an H240 controller in HBA mode and the output of the above cat command shows 512, lsblk also shows 512

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MLHJ
Occasional Advisor

Re: P440ar & battery: TRIM not supported w/RAID? Battery-backed write cache in HBA mode?

Thanks, much appreciated :)
Just to let you know TRIM is working after I took out the x4 SATA links from the RAID card and put them into the onboard. Which is a bit of a ($200) waste since the RAID card is unused now and I no longer have the 2GB write cache etc. But at least it works.

Jimmy Vance
HPE Pro

Re: P440ar & battery: TRIM not supported w/RAID? Battery-backed write cache in HBA mode?

Will report back with the P440ar results shortly, but wanted to state that the cache module is only enabled when the Smart Array is in RAID mode.

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Jimmy Vance
HPE Pro

Re: P440ar & battery: TRIM not supported w/RAID? Battery-backed write cache in HBA mode?

With both the H240 and the P440ar in HBA mode, the drive reported TRIM support. Drive is an older HP branded Samsung 100GB enterprise SSD.  Testing was done using a DL360 Gen9.

 

 cat /sys/block/sda/queue/discard_granularity
512

 

lsblk -D
NAME   DISC-ALN DISC-GRAN DISC-MAX DISC-ZERO
sda           0      512B       2G         1
├─sda1        0      512B       2G         1
├─sda2        0      512B       2G         1
├─sda3        0      512B       2G         1
├─sda4        0      512B       2G         1
└─sda5        0      512B       2G         1

 

 

 fstrim -v /
/: 48.6 GiB (52176195584 bytes) trimmed
 fstrim -v /home
/home: 34.7 GiB (37199839232 bytes) trimmed
fstrim -v /boot
/boot: 372.5 MiB (390631424 bytes) trimmed
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parnassus
Honored Contributor

Re: P440ar & battery: TRIM not supported w/RAID? Battery-backed write cache in HBA mode?

So could it be "only" an issue really related to using a non HP branded SSD (the Samsung 850, so not HP Firmware) on the P440ar in HBA mode?
Jimmy Vance
HPE Pro

Re: P440ar & battery: TRIM not supported w/RAID? Battery-backed write cache in HBA mode?

I'm not sure. I don't think I have access to any non-branded drives to test with.

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MLHJ
Occasional Advisor

Re: P440ar & battery: TRIM not supported w/RAID? Battery-backed write cache in HBA mode?

@Jimmy Vance: Thanks for cleaing up that the cache module only works in RAID mode! Then it doesn't matter whether I use the onboard SATA or use the P440ar (in HBA mode).

So it works with HP drives in HBA mode, that's odd. Another difference could be the Linux kernel version perhaps? Then again, I'm running 4.4.0 (default on Ubuntu 16 LTS) which isn't that old. What else? P440ar firmware version? The server is only a few weeks old, so.. I wouldn't expect any old firmware on it.

parnassus
Honored Contributor

Re: P440ar & battery: TRIM not supported w/RAID? Battery-backed write cache in HBA mode?

IMHO it shouldn't be a Linux 4.4 Kernel's fault (TRIM is supported [*] since about Linux Kernel 3.8, so many years ago...and Server class OS distributions generally backport newer Kernel features to their Kernel lines so watching the Kernel version itself is not so relevant as a parameter to judge the inclusion/exclusion of a feature)...provided that you haven't tested TRIM against a filesystem that doesn't natively support it (EXT3, as example), thing I believe you didn't since you know what you're doing.

Can you test with another Linux distribution: as example, CentOS 7 or Fedora Server? ...just to take the OS layer out of this equation.

[*] potentially OT but could be interesting to read this (which seems related to all Samsung 8xx SSDs).