IT Mode HBA cards with Raid Cards co-existing

[TheBay]

Hi,

I'm in the process of building a new server, I will be running ESXi Baremtal and putting a plan together regarding data.

For my storage I will be using a LSI9207i-8 (LSISAS2308 Chipset) which will feed my 8 port backplane on my supermicro chassis, Using ZFS on a VM.

I want to run 2 or 4 additional drives from another backplane, possible 2.5" laptop drives or SSD's.
In RAID 1 or RAID 10 just as an ESXi datastore for the VM's

What card should I get to do RAID1 or RAID 10, I'm assuming a LSI2008/IR based card would be fine as there is no XoR with those levels of RAID.

However I read somewhere that you cannot have IT mode running on one LSI card and IR/RAID on another?, is this true.

I would be interested to hear more about this, or what other people use and recommendations of a card that will work if a LSI2008 based card won't, or even a cheaper card that does decent RAID1/10.

Cheers.

 

[TheBay]

Does anyone have an idea of what the best card price/performance ratio I can buy to run RAID 1 or RAID 1-0 at hardware level for an ESXi data store, it has to work alongside my SAS2308 based LSI9207-i (IT Mode) which that is used for ZFS pools.

 

[apnar]

I have 3 SAS2008 cards passed through in IT mode and 1 SAS2008 card doing RAID10 for ESXi. Seems to be working ok. I may have turned the BIOS off on the pass through cards but don't recall for sure.

 

[TheBay]

I have 3 SAS2008 cards passed through in IT mode and 1 SAS2008 card doing RAID10 for ESXi. Seems to be working ok. I may have turned the BIOS off on the pass through cards but don't recall for sure.

What have you got hanging off the RAID10 configured card, how is write performance with no on board cache?.

 

[apnar]

What have you got hanging off the RAID10 configured card, how is write performance with no on board cache?.

4x 80g Samsung 830 SSDs. I did it more for redundancy of my VMs than performance but ended up with four instead of two cause the at the time 4x 80 were a good bit cheaper than 2x 160. As such I haven't done much of anything in the way of performance testing. I haven't noticed any real IO issues though with the stuff I'm using them for so it's passed the good enough test.

 

[TheBay]

4x 80g Samsung 830 SSDs. I did it more for redundancy of my VMs than performance but ended up with four instead of two cause the at the time 4x 80 were a good bit cheaper than 2x 160. As such I haven't done much of anything in the way of performance testing. I haven't noticed any real IO issues though with the stuff I'm using them for so it's passed the good enough test.

That's probably the route I'm going to take, looking at 60/64gb SSD's, lack of cache isn't really an issue with SSD's only spinners. Will consider the Samsung 830's, what is their garbage collection like? have had good results with Crucial M4's in everything, but only running on host OS so no idea what garbage collection is like running off a card.

And redundancy is my main focus with the ESXi VM Datastore, 128gb is more than ample for me as storage will be sat on the ZFS pools.

 

[dba]

The Samsung 830s have very good garbage collection - right up there with the Intel drives. You can improve write performance even more by formatting to use less than all of the available space - Google "overprovisioning". Leaving 25% free space does wonders to make write write latency more consistent. Leaving 50% free offers a further improvement, but a comparitively small one.

Separately, you might want to consider 128GB or 256GB SSD drives instead of 60GB. Most 60GB drives do not use all of the memory channels on the drive controller chip, which significantly reduces write speed. In fact, the 64GB size in particular often performs like half of a 128GB drive, but costs more than half. Write speed for the Samsung 830 is 160MB/S for the 64GB version, 320MB/S for the 128GB version, and then inches up to 400MB/S for the 256GB and 512GB versions. For these Samsung drives, 128GB is the "sweet spot" in the write speed per dollar performance curve. For some other drives it is now the 256GB version.

That's probably the route I'm going to take, looking at 60/64gb SSD's, lack of cache isn't really an issue with SSD's only spinners. Will consider the Samsung 830's, what is their garbage collection like? have had good results with Crucial M4's in everything, but only running on host OS so no idea what garbage collection is like running off a card.

And redundancy is my main focus with the ESXi VM Datastore, 128gb is more than ample for me as storage will be sat on the ZFS pools.

 

[TheBay]

The Samsung 830s have very good garbage collection - right up there with the Intel drives. You can improve write performance even more by formatting to use less than all of the available space - Google "overprovisioning". Leaving 25% free space does wonders to make write write latency more consistent. Leaving 50% free offers a further improvement, but a comparitively small one.

Separately, you might want to consider 128GB or 256GB SSD drives instead of 60GB. Most 60GB drives do not use all of the memory channels on the drive controller chip, which significantly reduces write speed. In fact, the 64GB size in particular often performs like half of a 128GB drive, but costs more than half. Write speed for the Samsung 830 is 160MB/S for the 64GB version, 320MB/S for the 128GB version, and then inches up to 400MB/S for the 256GB and 512GB versions. For these Samsung drives, 128GB is the "sweet spot" in the write speed per dollar performance curve. For some other drives it is now the 256GB version.

I did wonder if "Shortstroking" them would make a difference, thanks for that useful information.
Regarding speed, I know this was applicable to the M4 series (I have 128's and 64's) so it seems this is the same with other SSD's, Will get 2 128gb instead then. The 830 sounds promising!