SQL Server Performance Forum – Threads Archive

Server Config (SAS Concerns)

I have a dedicated SQL box that I am trying to replace. The system I am replacing is a Dual 1.2 GHz machine with 2GB RAM and 4 X 15K U320 SCSI in RAID5 (single channel) running SQL 2000. I am trying to buy a server that will last another 5 years – and I expect the box to be upgraded to SQL 2005 within 2 years of purchase. So, my goals for the new box were:
1) Dual core (single socket) 5100 series Woodcrest processors. This way I am only paying for one per processor SQL 2005 Standard license ($6000 per proc).
2) Double the RAM to benefit from increased SQL support (4GB)
3) Double (or more) I/O throughput (goal was 8 X 15K U320 SCSI drives over 3 channels) We use HP as our server vendor and they unfortunately are pushing SAS strongly enough that all generation 5 DL320, DL360, and DL380 servers only support SAS drives. If I jump back to Gen 4 I can’t get dual core procs! If I must have dual core and SCSI I have to jump up to a 570 box with external storage and more than double the cost of what I was going for. So, right now I am looking at: DL380 with Intel 5100 Series "Woodcrest" processors @ 3Ghz / 1333Mhz FSB, 4GB RAM, and 8 X 10K SAS internal drives. The 10K SAS drives have me concerned. I realize that the 8 10K SAS drives still likely increase my maximum random I/O rates and average seek times when under stress, but I doubt it achieves double. This is 90% an OLTP box and typically 15K drives are the gold standard for such workloads. My budget situation has essentially made this decision for me…but I’m wondering if there is anyone out there with a glaring warning about the 10K SAS drives for OLTP. Thanks in advance. Ryan

---

the name of the game is total IOPS and sequential bandwidth,
so 8 x 10K should be better than 4 x 15K
there are very few situations that need the lower latency of the 15K drive,
and those typically involve systems with several hundred disk drives where it is important to get the number of in-flight transactions down,
you will not see this as an issue in a system with 8 disks i do not know why you are complaining about not reaching 8x15K, the G4 can’t do that either i just got a Dell PowerEdge 2900 with 10 internal disk drives, then i shoved one more into the open 5-1/4 bay

---

I’m not complaining. I have a current G4 with 8 drives. 2 are internal (RAID1), 6 are stacked in an HP storageworks drive cage all on 1 channel. I never said they had to be internal. My goal had been a G5 (for Woodcrest) with 8 drives total: 2 internal (RAID1), and 6 in a storageworks add-on with 3 drives per channel. My server guys said that this was an invalid config for the G5 – I think G5 only supports SAS or something like that. Accordingly, if I wanted SCSI I had to go with the 570 (too expensive). If I go DL380 G5, the 8 internal SAS seemed like the most I could sell my managment team on. My only concern (not complaint) was latency – which you’ve commented on. Thanks. RH

---

as standard practice,
i would advocate 4-8 internal drives
10+ external drives this could be the MSA 50 for 10 SAS SFF drives
or the MSA30 with SCSI drives
use 2 SCSI channels for SCSI, SAS will use a x4 channel which is more than adequate i do not see why the external config is invalid, unless it is that you will need an addition SCSI RAID controller

---

It’s coming back to me now… The DL380 G5 only supports SAS internally. Your right, externally I could still get SCSI. My server team had a problem with having 2 SAS drives internal and 6 SCSI in the MSA. I’m following up to see if there was a hardware limitation or just personal concerns about mixing the technologies. I’ll post back when I know. RH

---

]]>