Perc 6i With 3TB Hard drive

Hello Stephane

The 11th generation controllers are the first to support 3TB HDDs(H700/H710,H800/H810,H200/H310). There is not a firmware update to provide 3TB support on the PERC 6.

I'm not sure why the SAS 6 would work with 3TB HDDs. My only guess is that they were not in an array. The SAS controllers have the capability of acting as a non-logical connector and do not force all HDDs to be in an array. All of our PERC controllers require all HDDs to be in an array to allow communication, so creating meta data for the entire drive is necessary in all circumstances.

Thanks

Many thanks daniel for you clear answer. in my situation it's a disaster (a nightmare even), i buy lot of perc 6i to replace all our SAS 6/IR without reinstalling windows (and also sas 6IR and perc 6I use the same connector). this work well except on the servers that have 3TO hard drive. now what you advise me to do :

1/ buy one H700/H710,H800/H810,H200/H310 ? but did the connector will be the same (we have poweredge 2950)? did i will need to reinstall windows 2008 R2 (actually only one single disk by raid volume).

2/ buy several 2 TO hard drive to replace our 3 TO hard drive... by the way why the controller can not use the 3 TO harddrive as a 2 TO harddrive ?

3/ wait for firmware update of the perc 6i (and revert to sas 6/ir in the waiting time) ? any hope ?

thanks by advance

stéphane

1.  The connector is NOT the same - you would need a new cable if you changed the SAS 6 to a PERC H-series.  Virtual Disks on the SAS 6/iR are not specifically listed as being a supported migration on an H700, although Virtual Disks that are boot volumes in Windows are not a supported migration for a PERC 6/i either - and PERC 6 VD's are supported for migration to an H700, so I suspect within those bounds, it would probably work.

2.  This depends ... some controllers that cannot recognize a >2TB disk may see up to 2TB of the space, or depending on the disk layout and mapping algorithms, it may see it as some other seemingly random sizes, like 746GB.

3.  There will be NO firmware update that will allow the PERC 6 to use >2TB disks - a new card, with updated hardware and programming is required.  There is no point in waiting for it.

One other thing I would be unclear on ... since the only way a SAS 6 can see a >2TB disk is in non-RAID mode, that means that no Virtual Disk has been configured on the SAS 6, meaning that RAID/VD metadata has not been written to the disk for the PERC 6 to analyze and import.  My "guess" is that you will be unable to import a non-RAID configuration on a SAS 6/iR into a PERC 6 at all, regardless of disk size, which means your best bet is to backup/restore for this transition, in which case, you may as well get the hardware you really want/need.

thanks theflash!

just a point: "although Virtual Disks that are boot volumes in Windows are not a supported migration for a PERC 6/i either"... in fact i thing no because i try and booting is ok ... i just need to first put the perc 6i in one available PCI slot, start windows to let him install the driver, shutdown windows, and replace the sas 6IR by the perc 6i and it's work !

"One other thing I would be unclear on ... since the only way a SAS 6 can see a >2TB disk is in non-RAID mode, that means that no Virtual Disk has been configured on the SAS 6, meaning that RAID/VD metadata has not been written to the disk for the PERC 6 to analyze and import."

yes i thing they was not in "raid" mode. it's a 'pity' that in perc 6i we can not have also this mode like in sas 6/IR :(

but i assure you the transition for server with harddrive < 2 GO work very great (even on boot harddrive). now your remark put me some trouble because the question is why it's work if no RAID/VD metadat have been written ?

It is not "supported" - I made no claim as to whether it works or not - many unsupported operations still work.  Dell's manual states that bootable Windows volumes cannot be migrated.

They make HBA's for SAS non-RAID - many high-end RAID controllers do not do both.

thanks theflash!

finally i will revert to SAS 6IR for the servers with 3 TO hard drive and for the other i will stay with the Perc 6i (actually it's look like to work, but if it's work optimal or not is another question) . just sad that the dell commercial never told me about such incompatibility :(

You are unlikely to get either from Dell.  Dell's answer to the 2TB limitation on the PERC 6/i is the H700.  

That said, it is a hardware limitation, and a firmware update cannot fix it.  If you need an explanation on how/why hardware is/can be a limiting factor on a controller with regards to the 2TB/disk limit, I would recommend asking your question on Experts-Exchange.com, as I know there are a few "experts" who can give you a better explanation than I can.

Would it be possible to double check the statements in Item 3?  The PERC H7XX series controller cards cost in the $800 range, and a half dozen 3TB hard drives cost about $900.  I just bought a T7500 with a PERC 6/i controller a few months ago and just found out empirically that the PERC 6 does not work with 3TB drives (I'm currently using 1.5TB drives).  If it is simply a matter of updating firmware, then I would hope for and expect Dell to utilize their considerable influence and have the PERC 6 manufacturer update the firmware, unless there is a specific hard and fast technical reason that the PERC 6 controller cannot be upgraded to sense and use 3TB drives (in that case I would expect a complete explanation).

as i can guess, 2 TB can use 32 bit pointer (2 TB = 4 294 967 296 sectors of 512 bytes, and this can fit in 32 bit architecture), but 3 TB must use 64 bit pointer !

so this mean to support 3 TB hard drive, the perc 6I firmware must be rewritten to support 64 bit, not an easy job, not an impossible job also (but also 64 bit use more memory than 32 bit) ... but i guess that commercially dell prefer to sell his H700 than spend money to update the firmware...

Is it possible a SAS 5 work in this same way, unofficially supporting 3tb HDDs as long as they're not in an array?

The SAS6iR on my Precision T7500 will only see the first 2048GB (2TB) of my 3TB drive (I had to connect it to the SATA controller on the motherboard for this reason). I suspect the SAS5 will yield a similar result where you can at best use the first 2TB of the disk (wasting nearly a third of it).

What I need to do to use the first 2TB in Perc 6i ? Thank you !

How much does it see?  Depending on the disk make/model and the firmware of the PERC, you may see 2TB automatically, or you may see substantially less - 760GB or even 0 - since they are not supported drives, it will be very hit/miss.

Sorry to *** in on this forum post, but with regards to the 2TB limit.

I heard a rumour on another forum that folks are using higher then the 2TB limit per drive on the PERC6/i cards, but this was only working on drives with a larger sector allocation is it the 4k sector drives?

anyway, I suggest someone give this a try and come back with some information, interesting subject heh

Sorry just passing through :)

I have an old R510 with a Perc6/i and as I had some 6TB WD Red Pro, I thought I would give it a try.  Turns out, it can only see the first 2TB.  It did immediately start a rebuild, so this is good for DR.  So the conclusion is PERC6/i will only see 2TB, 4K drives do not make a difference.