Dell DAS, SAS drives or SATA.

Andri

Andri

Andri

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hi all...
seems quite roomy in here at the moment. (i think this is the right place for this type of question or would HDD forum be better?)

just looking for a few ideas on what to pack out a DAS box with.

we are currently in the process of moving most of our servers to virtualisation.
We primarily do MS SQL database development and we have a rough idea what we are going to do as far as server configuration.

I’m just looking few a few different ideas from the folks at OCUK.

Right the question’s.

We have a Dell Powervault MD 15 slot DAS, it came with 2 74GB SAS drives and 5 146GB SAS drives(all 15k).

Would we be better off sticking with more higher capacity SAS drives or just getting loads of cheap high capacity SATA drives?

Speed isn’t a huge concern at the moment.
 
in my experience SAS drives have proved more reliable than SATA, though traditional SCSI is still the way if cost isn't a big issue
 
I've had a nightmare with a few SATA drives in the past, so I'd stay safe with SAS drives especially when working with databases.
 
Hi there,
thanks for the replys

Unfortunately SCSI isn't an option.
i have also noticed that this DAS box is very picky about what SATA drives it likes as well.

So SAS is definatly the way to go.
 
my experience (HP MSAs are the only DAS we use) are that SATA is very reliable even compared to SAS, the SAS attached arrays are also pretty quick, perhaps better than u320 SCSI though I haven't benchmarked...
 
SAS drives all the way, they are faster and more reliable, as they are essentially SCSI disks with a different interface.
 
If it's capacity you want, and aren't bothered with spindle speeds (especially when you take into account write penalties such as RAID 5) then SATA will be fine.

If you require more drives, more spindle count, and faster spindles, then SAS.

All down to where your priorities lie. The good thing with the MD series of arrays is that you can mix and match SAS and SATA drives in the same bank of 15 drives (must be on seperate RAID & LUNs though.

BTW - SAS stands for Serial Attached SCSI, different connectivity (point to point vs parallel) but the underlying HDD technology is the same.
 
Tough one. SAS drives are more reliable on paper and probably have higher quality components in, however SATA's are still reliable, cheaper (in £'s per GB) and can still be fast if you get the right drive (e.g the new 333Gb per platter drives).

If you're worried about reliability you could just go Raid 6 as long as you have the Dell Perc 6 which will let you tolerate two disk failures. 4 x 1TB SATA's in Raid 6 would give you 2Tb storage at not much £'s. 6 x 1TB would give you 4TB. Don't forget btw that you need to buy SATA 2 disks. Sata 1 disks won't be compatible.
 
The real advantage of high rpm SAS is not reliability, which should be achieved with redundancy, but high random IOs. If you are not doing hundreds of random IOs per sec then the extra storage you get with SATA might be more advantageous. As Nick pointed out, you don't even want to think about non SAS SCSI drives.

Be sure to check out the storagereview forums.
 
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Hi all,

thanks for all the information.

at the moment i am starting to lean towards SAS drives.
As far as SATA drives go from what i have read about our dell PowerVault it is very picky about what make SATA drives it uses.

i am aware that i will need SATA 2 drives but also need to find out what SATA 2 drives are compatable with this PowerVault.
 
We've recently moved from SCSI to SAS drives in our IBM servers and the SAS drives are light years ahead in terms of speed.
I wouldn't even entertain SATA, personally.
 
We get Dell 2950s with 5 x 300GB 15k SAS drives in RAID5 plus a hot spare as our main machines these days. Performance has been exemplary.
 
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