Web Hosting Talk : Web Hosting Main Forums : Dedicated Server : 7.2k SATA in Raid10 or 15k SAS in Raid1

[diesel12]

We currently have 7.2k disks in Raid1 and have low enough activity that I/O bottlenecks are not an issue. Wanted to upgrade to 15k disks in RAid1 when we upgrade our CPU to prevent issues as we grow, but realized that we could also do 7.2k disks in RAID10 which would enable us to stripe as well.... wondering which would be faster: 7.2K SATA in Raid10 or 15k SAS in Raid1 ?

Any feedback greatly appreciated!

[24x7group]

The SAS disks are fast, but if you really want a top performance, put the SAS disks in a RAID10 setup
If that's not possible, a RAID10 with SATA disks will give a bit better performance than the SAS disks in RAID1.

[Jacob Wall]

I think the difference would be negligible, but I could be wrong. I would stick to RAID 10 w/ SATAs because of two reasons. First off, SATAs are cheaper and secondly you can have two drives fail(So you don't have to hover over your RAID status all the time in fear).

[FHDave]

Depends how many drives you have in the SATA RAID10.

If we take just 100% random I/O then 15K SAS drive can do 200-ish IOPS whereas 7.2K SATA drive can only do ~70 IOPS. So for I think (need to verify this) you will need more than 6 drives of SATA in RAID10 to make it comparable to 2 drives of SAS 15K drives.

I could be wrong. But to claim that 7.2K SATA drives in RAID10 will always perform faster than 15K SAS drives in RAID1 is just plain wrong.

[diesel12]

FHDave: our option is 4 sata disks in raid 10 ....

[plumsauce]

Originally Posted by FHDave

I could be wrong. But to claim that 7.2K SATA drives in RAID10 will always perform faster than 15K SAS drives in RAID1 is just plain wrong.

Especially when one does not take into account the particular controller, and, the cpu load difference.

[diesel12]

We're looking at an average cpu load of .50% with 4 cores, so very low and the following controller.... Adaptec 2405 PCIe - 0.8GHZ Dual Core - 128MB Cache.

[FHDave]

Originally Posted by Jacob Wall

First off, SATAs are cheaper and secondly you can have two drives fail(So you don't have to hover over your RAID status all the time in fear).

The idea that you can have two drives failure in RAID10 and still be OK is not necessarily correct. It depends on how many dirves you have and which set of drives fail. RAID10 is a strip of two RAID1 arrays. If you only have 4 drives in RAID10, then yes, your RAID10 may fail in the way just like any RAID1.

Besides, in average, SATA drives often fail more than SAS.

[FHDave]

Originally Posted by diesel12

FHDave: our option is 4 sata disks in raid 10 ....

I am pretty sure with only 4 SATA drives, I will go with 15K SAS drives in RAID1.

[Jacob Wall]

Originally Posted by FHDave

The idea that you can have two drives failure in RAID10 and still be OK is not necessarily correct. It depends on how many dirves you have and which set of drives fail. RAID10 is a strip of two RAID1 arrays. If you only have 4 drives in RAID10, then yes, your RAID10 may fail in the way just like any RAID1.

Besides, in average, SATA drives often fail more than SAS.

True, I should of clarified that. I learned something new, never knew that SATAs failed more often than SAS.

[diesel12]

You have a point with the SATA's failing, have had at least two failures in the last 4 months alone.... possibly 3 in last year, if my memory is correct.... in this scenario, the cost is the same for sata raid10 and sas raid1, hence the question.

[mds85]

I wouldn't blame SATA over the fact that many cheapskate hosts use desktop-grade disks in their systems. Use a server-grade SATA disk and get back to me.

Saying SATA is less reliable than SAS without basing facts is atrocious.

If you're using a desktop drive 24/7/365 in server conditions, then yes, it's going to fail it's not made for that. Before we start saying 'LOL SATA FAILS!!!1!', lets state what brand, model, and grade it is.

[FHDave]

Seems like somebody gets offended

Originally Posted by mds85

Saying SATA is less reliable than SAS without basing facts is atrocious.

Are you saying we should not even trust the manufacturer on specs?

Compare Seagate 7.2K Baraccuda ES.2 vs. Seagate 15K Cheetah. Pay attention to the MTBF and annual failure rate number.

I do agree that Enterprise SATA drives are more reliable. But even the manufacture claims higher reliability on the their SAS drives.

Perhaps you can state the SATA and SAS brand, model, and grade where it actually has the same or better MTBF and failure rate than its counterpart SAS drives? Let me know.

[plumsauce]

Originally Posted by mds85

Saying SATA is less reliable than SAS without basing facts is atrocious.

If you are aware of facts which are not presented, that you think should be presented, then please present them.

It is a *fact* that in written documentation, both HP and DELL state that in those disk arrays which are capable of using SATA or SAS drives, that the SATA configurations should be considered only for *secondary* non-critical storage and the SAS configuration is for *primary* storage. This is from the vendor who has to support them and warranty them, as well as still trying to make a profit.

Please be aware that the IBM/HP/DELL/SUN supply chains get the cream of the crop when buying from the disk vendors. This is because they get to make the disk vendors eat any warranty returns, no questions asked, just send the money or replacements. Those cherry picked drives in real life use are much more reliable than the vanilla retail chain drives.

You will also see little enhancements that are reserved for these drives. For example, vibration dampers that you will not find except on these drives and only on that particular server brand.

[VINAX]

I would go with RAID1 2x 15k SAS drive which is a bit faster than RAID10 4x 7.2k SATA drive. Also, SAS drives are more reliabe than SATA drives!