Best practices for connecting SATA drives to SAS controllers?

F

frijsdijk

We're in the process of testing a low-cost SSD-based storage machine for backup purposes. This machine will do most of the heavy work (comparing for differential backups, and then transferring results to offsite storage), hence the SSD based storage. We need alot of IOPS and throughput in this machine.

We currently use a SuperMicro X9DRD-7LN4F(-JBOD)/X9DRD-EF for this, which has a SAS2308 on board, and we've chosen to use use 6 "Samsung SSD 850 EVO 1TB" drives in RAID5. The performance is awsome to say the least, but it's proven to be unreliable/unstable. We get alot of SCSI resets and devices seem to dissapear under heavy load. The machine will need a powercycle to 're-see' the drives, a reboot doesn't even cut it.

I've some some searching, and I'm reading alot of 'no-gos' in the area of connecting SATA drives to SAS controllers via IPASS connectors.

http://garrett.damore.org/2010/08/why-sas-sata-is-not-such-great-idea.html
http://omnios-discuss.omniti.narkiv...rget-hang-no-way-to-restart-but-server-reboot
https://utcc.utoronto.ca/~cks/space/blog/tech/SASWithSATAIntro

Obviously it would be nice to connect the drives to a native SATA HBA, but these are hard to find. And SAS SSD's are just too expensive.

Now this machine is a Linux based machine, not FreeBSD, but I've found that people have the same issues in FreeBSD. Obviously we're doing something wrong, and I was wondering if somebody with proper storage knowlegde can give some advise.
 
Samsung SSD 850 EVO is a customer grade SSD and not enterprise so its not designed for heavy usage. I've researched this and decided to go with Crucial MX200 for my production servers. Crucial MX200 SATA SSD is 'customer' grade but its near enterprise grade. It's not expensive nor cheap. I installed LSI SAS 9211-4i SAS/SATA adapter in my Tyan server. It works very well even under heavy load. I don't trust onboard SAS controllers if it doesn't have LSI or Intel chipset.

I had to flash a different firmware for LSI SAS adapter so it'll boot as non-RAID card as my server uses ZFS.

LSI 9211 doesn't have cache built-in but not needed for SSD.
LSI 9240 got cache and its better suited for HDD.

Hope this helps.
 
The MX200's look fine indeed. Same MTBF though.. I suspect it's mainly our controller/cabling to the drives, not the drives themselves.
 
frijsdijk said:
The MX200's look fine indeed. Same MTBF though.. I suspect it's mainly our controller/cabling to the drives, not the drives themselves.
Click to expand...

Or it could be faulty SAS driver or firmware. I doubt it's the SATA cable though.

Try the controller card with the kit as it comes with mini-SAS to SATA cable if you still have the problem. The last thing you want to do is replace all SSDs.
 
@all, the OP wants a cheap solution for SSD. So going enterprise is out of the question here. frijsdijk , we have the same controller and I have been informed from a reliable source that the latest firmware has problems with FreeBSD 10.X What version are you using?
 
gkontos: what does this tell you?

Code: 
lspci:
03:00.0 Serial Attached SCSI controller [0107]: LSI Logic / Symbios Logic SAS2308 PCI-Express Fusion-MPT SAS-2 [1000:0086] (rev 05)

Code: 
# ./sas2ircu 0 DISPLAY
LSI Corporation SAS2 IR Configuration Utility.
Version 20.00.00.00 (2014.09.18)
Copyright (c) 2008-2014 LSI Corporation. All rights reserved.

Read configuration has been initiated for controller 0
------------------------------------------------------------------------
Controller information
------------------------------------------------------------------------
  Controller type  : SAS2308_1
  BIOS version  : 7.31.00.00
  Firmware version  : 16.00.01.00
  Channel description  : 1 Serial Attached SCSI
  Initiator ID  : 0
  Maximum physical devices  : 255
  Concurrent commands supported  : 3072
  Slot  : 5
  Segment  : 0
  Bus  : 3
  Device  : 0
  Function  : 0
  RAID Support  : Yes
------------------------------------------------------------------------
 
frijsdijk said:
Well, that's by far not the newest version. I've found version 20.00.02.00, but haven't flashed yet. I'm using this machine with Ubuntu 14.04.2, kernel 3.13.0-46-generic #77-Ubuntu.

http://www.lsi.com/products/host-bus-adapters/pages/lsi-sas-9207-4i4e.aspx#tab/tab4
Click to expand...

Sorry, my bad. I am using: Firmware: P19. I was told that P20 has some issues with FreeBSD 10.X. You are using Ubuntu so I can't really advise on that. Any particular reason that you are not using FreeBSD?
 
gkontos said:
Sorry, my bad. I am using: Firmware: P19. I was told that P20 has some issues with FreeBSD 10.X. You are using Ubuntu so I can't really advise on that. Any particular reason that you are not using FreeBSD?
Click to expand...

Hmm well, we haven't even considered FreeBSD for this to be honest, Linux (Ubuntu 12.04 and up) has proven to be alot more stable under high loads in our case. But I don't want to start a holy war here :) . I still think FreeBSD rocks.
 
My SAS controller also got P19 as well but it got 2004 chipset. P20 does have issues with FreeBSD 10.x.

I don't have issues with my (3) SSDs in my server even under heavy load.

You may want to try to flash your firmware to P19 and see what happens but again you're using Linux SAS driver.
 
frijsdijk said:
Hmm well, we haven't even considered FreeBSD for this to be honest, Linux (Ubuntu 12.04 and up) has proven to be alot more stable under high loads in our case. But I don't want to start a holy war here :) . I still think FreeBSD rocks.
Click to expand...
No holy wars please :)

Like, Remington said you could try upgrading the firmware but you would still be using a Linux driver. Try doing that and if it does not help and you still want to use Ubuntu then you can ask at the Linux mailing list.
 
Hi, we're seeing the exact same issue with 850 PRO's with SAS 2308 cards in SuperMicro boxes. Did you ever find a resolution to this? We're running CentOS 6.6
 
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