I have 8 WD SATA HDD with raid ready (3mbps) hard disks on a 8 port 3ware controller.(on raid 5.) Does anyone have a comparison on SATA raid and SAS raid disk. As you know SAS disk are very expensive and I would like to know from experts in the list who could suggest which of the following would be the best. Option 1) 2 servers each having 2.0TB raid disk with SAS drives, 2GB ram and standard other features. Option 2) 4 No servers with 1TB each with 2GB ram and standard other features. If Data files (mostly AutoCAD Drawings of size 5MB to 50MB) are distributed as per the above options do you think which could perform better?. As you know the price of SATA disk is much cheaper than the SAS disk and we could nearly by 4 servers for that money. Probability work disturbed by a server crash is low in the second case but I am not sure about the comparison on performance. I would appreciate if you could spread some thought in this regards, and apologize if this is out of topic. Best regards, Rajeev -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.centos.org/pipermail/centos/attachments/20070822/220bfc1d/attachment.html>
On Wednesday 22 August 2007, Rajeev R Veedu wrote:> I have 8 WD SATA HDD with raid ready (3mbps) hard disks on a 8 port 3ware > controller.(on raid 5.) Does anyone have a comparison on SATA raid and SAS > raid disk. As you know SAS disk are very expensive and I would like to know > from experts in the list who could suggest which of the following would be > the best.I got a 4 port 9650 with 4 750GB Seagate drives in raid 0+1 on it for data storage, and a 8port LSI LSI00110 with 4 36GB 15K rpm disks, again raid 0+1, for the OS and swap. When I take a ext3 filesystem and run bonnie++ then the SATA solution is about 60% faster for sequential reads. However, for random access, the SAS solution is about 3 times faster. So - as always in this world - the answer depends on your usage pattern.> Option 1) 2 servers each having 2.0TB raid disk with SAS drives, 2GB ram > and standard other features. > > Option 2) 4 No servers with 1TB each with 2GB ram and standard other > features. > > If Data files (mostly AutoCAD Drawings of size 5MB to 50MB) are distributed > as per the above options do you think which could perform better?. As you > know the price of SATA disk is much cheaper than the SAS disk and we could > nearly by 4 servers for that money.Its been a while since I did AutoCAD but anyway - why only 2GB? As for the IO, AutoCAD (assuming you have enough ram so your system doesn't swap) doesn't do a lot of i/o - and if so, its mostly sequential. So, without having tried it, my guess is that you will not see much of a difference either way. I'd go with the 4 servers. On the other hand, data reliability is another issue. We have tons of sata based disk arrays and have had no issues yet (because our systems are all on UPS and multiple circuits) but if you don't have infrastructure like that, you are more likely to lose data on a sata based system... I personally would still go sata. Peter.
> -----Original Message----- > From: centos-bounces at centos.org > [mailto:centos-bounces at centos.org] On Behalf Of Rajeev R Veedu > Sent: Wednesday, August 22, 2007 2:52 AM > To: 'CentOS mailing list' > Subject: [CentOS] SATA vs. SAS > > I have 8 WD SATA HDD with raid ready (3mbps) hard disks on a > 8 port 3ware controller.(on raid 5.) Does anyone have a > comparison on SATA raid and SAS raid disk. As you know SAS > disk are very expensive and I would like to know from experts > in the list who could suggest which of the following would be > the best.As a lot of people have probably said the answer depends on your workload. If the workload is mostly small random io I would go with 15K SAS configured into a raid10. If the workload is mostly fairly large sequential reads/writes (file server) then I would probably go with SATA 7200 RAID5/6 or RAID50/60. If doing databases set the chunk size to the maximum size of a data dump i/o (usually 1MB) so each dump i/o hits a separate spindle, for random it doesn't really matter cause it's random, you just want the fastest access time money can afford. For file services you will have to gauge the chunk size by the type of files, mostly small, small chunks, mostly large, then larger chunks, 64K is the standard middle-of the road here.> Option 1) 2 servers each having 2.0TB raid disk with SAS > drives, 2GB ram and standard other features.If going down this road, why not look into getting one of those fancy new storage enclosures where the RAID is built into the enclosure and can allow 2 servers to simultaneously access the arrays with full battery backed write-back cache?> Option 2) 4 No servers with 1TB each with 2GB ram and > standard other features.I don't know if I follow you here...> If Data files (mostly AutoCAD Drawings of size 5MB to 50MB) > are distributed as per the above options do you think which > could perform better?. As you know the price of SATA disk is > much cheaper than the SAS disk and we could nearly by 4 > servers for that money.If that's the workload, then save the money and go SATA in a RAID50 (two RAID5's striped), say a 4-spindle/4-spindle if you could go to say 10-12 disks then do a 5-spindle/5-spindle with 1 or 2 hotspares.> Probability work disturbed by a server crash is low in the > second case but I am not sure about the comparison on performance.Look at a shared storage solution so you can have the storage fail-over in the even of a server crash rather then replicate it.> I would appreciate if you could spread some thought in this > regards, and apologize if this is out of topic. > > > > Best regards, > > > > Rajeev > > > >______________________________________________________________________ This e-mail, and any attachments thereto, is intended only for use by the addressee(s) named herein and may contain legally privileged and/or confidential information. If you are not the intended recipient of this e-mail, you are hereby notified that any dissemination, distribution or copying of this e-mail, and any attachments thereto, is strictly prohibited. If you have received this e-mail in error, please immediately notify the sender and permanently delete the original and any copy or printout thereof.
Peter Arremann wrote:> > On the other hand, data reliability is another issue. We have tons of > sata based disk arrays and have had no issues yet (because our systems > are all on UPS and multiple circuits) but if you don't have > infrastructure like that, you are more likely to lose data on a sata > based system...Why do you say that SATA arrays are less reliable? I have used both SATA and SCSI raid and have had drive failures on both. Recovery from the failures seems to be more a matter of the raid implementation than the interface type. -- Bowie
Feizhou wrote:> > > Option 1) 2 servers each having 2.0TB raid disk with SAS > > > drives, 2GB ram and standard other features. > > > > If going down this road, why not look into getting one of > > those fancy new storage enclosures where the RAID is built > > into the enclosure and can allow 2 servers to simultaneously > > access the arrays with full battery backed write-back cache? > > > > What is available for Linux in this department?http://www.coraid.com/ These are relatively inexpensive network storage boxes using SATA drives and AoE (ATA over Ethernet) connection to the server. Drivers build easily on CentOS. Just make sure you get drives that are on their compatible list. This may not be as much of an issue now, but I had some problems with drives being marked bad and dropped out of the array when I first set up mine a couple of years ago. This was caused by firmware incompatibilities and fixed by upgrading the drive firmware. Once this was fixed, everything has worked flawlessly since. -- Bowie
On Wednesday 22 August 2007, Rajeev R Veedu wrote: ...> Option 1) 2 servers each having 2.0TB raid disk with SAS drives, 2GB ram > and standard other features. > > Option 2) 4 No servers with 1TB each with 2GB ram and standard other > features.Late comment on this thread. Really short comment actually: SAS vs. SATA is not the issue, raid controller A vs. B is. /Peter -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 189 bytes Desc: This is a digitally signed message part. URL: <http://lists.centos.org/pipermail/centos/attachments/20070823/a6129077/attachment.sig>