Global Storage

Hi Antonis,

The FlashSystem 5600 requires a minimum of six drives. Use six 13.2 drives instead of three 26.4 drives with DRaid6 for almost the same price, higher redundancy, and greater capacity. 

Therefore any number of FCM5 below 6 modules is not a valid config?

I disagree with Nezih, according to latest config limits, two disks is the minimum for DRAID-1 and four for DRAID-5 (for all supported hardware, not just 5600).

See: https://www.ibm.com/support/pages/node/7256231

But if you use DRAID-6, then six disks is minimum as Nezih already mentioned.

Remember that minimums are not the best or recommended way to go, missing additional fault tolerance.

Only FS5600 supports DRAID1 and DRAID5.

FS7600 and FS9600 only support DRAID6.

Yes, Uwe is absolutely correct. But I believe Antonis and his customer were asking for 5600. Especially when they have budget, then the bigger options are far out of reach.

Hi everyone, I asked this question a while back to Modeller support, and this was their response.

e-config doesn't have any issues with creating a smaller config.
I think that the bigger issue is that it will not take advantage of the parallelism of the system. The general recommendation for FlashSystems is to use at least half of the drive slots so that you can spread out the IO. I'm not sure what the performance would look like with only 1/4 of the slots used.

Thanks for all the provided answers. Indeed checking Storage Modeller does not allow this config but i believe it must be fixed soon. Fully agree that this config is not recommended and does not take advantage of the system but given the fact that 5600 is the smallest system with FCM support i believe it is a logical decision from IBM to suport DRAID1 and allow configs with a smaller number of FCM.

Dear all

I had this question discussed with jorge a view weeks ago. Please have a look at the actual announcement letter, it was revised and now it tells us, that 6,6TB, 13,2TB and 26,4TB Drives can be used for DRAID1. Also IBM offers now Valuebundles with 2 of three have exact this configuration
2x 13,2TB Drives and 2x 26,4TB Drives as initial config

I agree, that STORM didn´t have a bug, but a feature is missing! The workaround is to build a FS5300 with smaller drives an calculate the result with the multiplier of Capacity differences.

That´s the way i overcome the issue. The bad thing : i cannot give a capacity nor a performancesheet to the BP or customer :-(

kind regards Martin

@Martin Haussmann

I'm concerned because a business partner mentioned to me that on an FS5600, they tried to configure DRaid 1, but this option is disabled; apparently, it's restricted.

Hi Antonis... My experience with creating DRAIDs is that you have additional options for creating arrays from the command line instead of the graphical interface.

Try experimenting with some commands. I've changed some values ​​from the command line that the graphical interface didn't allow, such as (for example) creating a RAID5 (not a DRAID) or changing the number of internal groups.

With the latest Update today of STORM : FS5600 is capable of DRAID1 Calculation (also DRAID5)

Well, this time mkdistributedarray command have some missing parts according to IBM Docs. draid5 is not an option.

https://www.ibm.com/docs/en/flashsystem-5x00/9.1.2?topic=commands-mkdistributedarray

We support DRAID-1 with the 26.4 and smaller drives
We support DRAID-5 is only supported on the 5K series (hence it is not in the pubs arguments) and is only recommended for FCM-S and FCM-M at the 4-5 drive mark
If you are using 6 or more drives, use DRAID-6, if you are using a small number of Large drives (as in 20TB or larger) I would recommend looking at buying double the amount of small drives instead as you will get better fan out and better failure protection.  Keep in mind a single medium error during DRAID-1 or DRAID-5 rebuild is data loss, which is why for the 7 and 9K we really pushed to DRAID-6.  

For the 5K we acknowledge there are price concerns so we wanted to provide the smaller capacity options (2 drive configs and better capacity for 4/5 drive configs) and have instead restricted the drive size support to allow for those configs with the best possible MTBF.