SATA Versus SCSI RAID 5

[owensdj]

I'm looking at adding more storage space to a Windows Server 2003 machine that functions as a Active Directory domain controller, DHCP, DNS, and file server for a 15-20 client office network of XP machines. The server currently has 2 36.7GB 10,000RPM SCSI drives in a software mirror set for a total of just 36.7GB of space.

I was thinking that putting the shared data on a hardware RAID 5 volume using 3-4 drives would be the way to go. How would a SATA RAID card compare in terms of performance to a SCSI RAID card? I assume the SCSI RAID would be faster, especially if I used 15,000 drives, but would it be noticable enough to make it worth the extra cost?

 

[imported_Tick]

Ah, now we get down to the question of "How Much Is Speed Worth To Me"? Because 15k drives are faster, certainly, and 10k drives are faster than 7.2k, and SCSI in most cases is faster than SATA, however SAS trumps em all. Further, RAID 5 is fast, but RAID 50 is faster. It all comes down to, again "Ho Much Is Speed Worth To Me"? Is there a budget? What kind of files is this thing dealing with? How much traffic do you get? What's the rest of the system? Is speed a huge concern? How long before this machine is replaced altogether?

 

[owensdj]

Tick, there is no set budget. It's whatever I think is appropriate for the upgrade project, within reason. The files are mostly multiuser programs that access shared database files on the server. The heavy use of the server comes during tax season(January - April 15th) when it will have 15-20 tax preparers running multiuser tax preparation software. The server is a 2.26GHz 533MHz FSB P4 with 1GB ECC memory. Yes the main concern is speed. The faster that tax software runs the more tax returns they can do, which means more money. The server is almost 3 years old now. I would imagine it will be replaced either before the beginning of next tax season or the year after that.

 

[imported_Tick]

Ok. Assuming you have a 2 PCI-X slots, RAID 50 would serve you well. Get 2 raid 5 controllers, SCSI, Get 8 15k drives, set them up in a striped set of 3 drive RAID 5 arrays, with a hot spare on each controller. Make sure you get controllers that are capable of controller duplexing. SAS is a possibility if cost is really no concern, however, SAS (Serial Attached SCSI) is just getting it's feet wet, so it isn't very wide spread, and very few drives and controllers support it. However, it is the way of the future in the enterprise server market. SAS drives offer great burst speed, and throughput. If you choose to go SAS, I would still recomend RAID 50 with controller duplexing. This offers advantages in speed, as well as allowing for controller loss without data destruction. Also, RAID 50 offers very good storage effeciency, as it only looses one drive capacity per RAID 5 array. This sort of setup is highly efficient at handleing multiuser, multifile situations. One thing you may want to consider adding with the new array would be another 1gb of ram, as a situation with that many users will benifit from it.

 

[jose]

I just built this about 2 months ago for about $6K more or less. If your server is already 3yrs. old, get a new one.. preconfigured Dell or IBM..


But if you want to build it your self, here's a start. I just built this server 2 months ago for $6K, so you may be able to get it a little cheaper..

Tyan K8W dual opteron mobo
4 - 1 gig reg. ecc mem modules
2 - Opteron 248's
LSI 320-2X scsi controller
LSI scsi host bust adapter for the tape drives
8 - Fuj. 15k 36g scsi drives
2 - Supermicro hot swap enclosures
1 - dds4 tape & another dds4 that they already had
some NV 5200 video card
Zippy 700w psu in a CM Stacker case.

This system would more than capable to support the 20+ users.


But if you just want to upgrade your current server which seems to be dated already, you could add a scsi raid controller & 2 more scsi drives and do raid 5.

But remember your server is slow already, tell them it's time to upgrade.

The Opteron server that I built replaced a Dell poweredge dual p3 w/ 2 gigs of ram and a raid5 disk system. Some database progs took 12 hours to run, now they take 20min. to complete.

Good Luck,
Jose

 

[imported_Tick]

As he already stated, he's only looking to upgrade there storage.

 

[ReliableData]

Originally posted by: owensdj
especially if I used 15,000 drives

lol....i know what you meant, but still, lol

 

bump

 

[owensdj]

ReliableData, haha oppps. Yeah I mean 15,000RPM drives.

Jose, thanks for the server info, but do you really think I'd see any performance increase from a faster processor(s)? The server only handles about 20 users right now and doesn't do much local processing such as running an SQL database server. It's a Active Directory DC that does file, DNS, and DHCP server service for a single domain. I was thinking it would benefit more than anything else from adding a RAID card and having 4 drives in a RAID 10 configuration.

 

[jose]

The server I listed in my example benefited greatly from the fast I/O subsystem.. It's running RedHat ES , and a Unify database in addition to a firewall(iptables), proxy(squid) & samba. So it's mostly I/O bound by the database, but everything runs smoothly.. In the past the database and the odbc damon were communicating too slow w/ each other because of hit's on the firewall. We had to manually slow down the damon because it would report error's to client apps. when there was no error.. The database took to long to respond to the damon..

Granted the specs may be more than you need, but consider the price & what your getting for it..

You need a balanced system, not just fast hd's or just a fast processor.. Your biggest improvement would be getting a better I/O sub system.
But you said you had a P4 not a Xeon system, which means you probably don't have any 64bit pci-x slots. Do you have any 64bit pci-x slots ??

Regards,
Jose

 

[owensdj]

Jose, no the server doesn't have any 64-bit PCI-X slots. As I understand it, the LSI MegaRAID 320 card will work in a 32-bit PCI 2.2-compliant slot. I know that using a 32-bit PCI slot will hold back the performance a bit. At some point the RAID card and SCSI hard drives will be moved into a new dual processor server that will support 64-bit 66MHz PCI.

 

[jose]

If you decide to go w/ 10k or 15k scsi drives, 3 will saturate the 32bit pci bus. I get 67 MB/s sustained on my atlas 15k drive and my atlas 10k4 get 60 MB/s sustained..

Try to get a mobo/server w/ 64bit 133mhz pci-x slots, you'll have better results..

I'm not sure if a LSI 320-2X would work in a 32 bit slot...

Look at computer giants for your scsi drives , they have great prices on Maxtor & Fujistu scsi drives...

Regards,
Jose

 

[ND40oz]

If you don't have any PCI-X slots, I wouldn't bother going with SCSI, you're not going to see a performance difference between it and a sata raid array running on the PCI bus. Honestly, that "server" is just a desktop box with Win 2k3 installed on it, you're better off using the most reliable desktop parts rather then trying to stuff server parts into a desktop box.