Seagate Momentus XT Raid Configuration Options

Wondering if anyone has any insight into this.

Raid 0 2xMomentus XT? Peformance?

Raid 0 1xMomentus XT 1x500GB 7200RPM drive. Is this even possible? Possible conflicts? I know that the Momentus is 32MB cache while the normal drives run at max 16MB.

Raid 1 options?

The reason i ask is because I have an Alienware M17x comming that includes a 500GB 7200RPM drive (most likely Seagate). And i'm trying to figure out possible configurations for using both drives. Without having to buy a second momentus XT if its avoidable.

 

When you put two unequal drives in Raid 0, the performance will default to the least common denominator. So for instance, a 500GB momentus XT and 160GB 5400rpm drive in Raid 0 will perform just like two 160GB 5400rpm drives in Raid 0. So by putting a momentus XT in Raid 0 with the existing drive, you are just wasting your money since it will not perform any better than if you got a regular 500GB 7200rpm drive. The exact same thing will be the case with any Raid level actually.

 

So, If i have the 500GB Momentus XT and a 500GB Momentus. Both running at 7200RPM, the 4GB Nand Flash will negate itself?

And If you have both similar drives Momentus XT in Raid 0 how will the 4GB Flash memory react? will you end up with 8GB?

 

Yes. The 4GB of flash memory will be used, but it will not improve performance.

No. The solid state memory isn't shown as a separate drive, but just used 'intelligently' by the drive to increase performance. You will however benefit from the performance increasing imparted by the hybrid design.

 

So... can i assume that running this in a raid 0 configuration will give me the benefit of the momentus XT's 4GB Flash Memory as well as the improved (slightly) Performance of a 1TB Raid 0. And will the XT's intelligent algorithms include the information from the secondary drive included in the Raid?

 

The performance benefit of the 4GB of flash memory is not transferable. It is completely invisible outside the drive. The only reason you know it is there is because Seagate tells you so. It just functions within the drive to boost performance. You can only get momentus XT performance in Raid 0 with 2 momentus XT's.

A situation similar to what you are asking would be pairing a 10k rpm drive with a 5400rpm one. No matter how fast or powerful the 10k rpm drive is, the two drives in Raid 0 will only perform as well as two of the slower drives, and there is no way to get around this.

 

Ah, i think I wasn't clear before when I asked if it would negate itself with 2 drives one being the XT and the other a regular drive. I meant to include that they would be in a Raid 0 and thus negating the XT's benefit.

 

That's right, there would be no benefit of an XT when in Raid 0 with a regular.

 

so basically u need 2 XT's...

 

And why exactly do you want RAID0?

 

Because it's faster, would be my guess. But, yes, as has been said, using dissiimilar drives in a RAID array is a bad idea. I have ordered a pair of XTs that I am going to configure into a mixed RAID0/RAID1 array (two volumes) for my M6400. As soon as they ship I can tell you how this works...

 

Cool, i've ordered my Single XT this afternoon so I should have it by the weekend I hope. Later on if i find i need the Raid configuration i'll upgrade to a second.

 

You're going to have them completely separate and not Raid 0+1, right?

 

No, I'll have them in a matrix-RAID config just like my current drives. System partition is on the RAID0 volume for performance, original data are on RAID1 for data protection. Best of both worlds.

 

Yeah, that's what I was asking. Each drive split in two with half of each drive going to Raid 0, and the other half going to a completely separate Raid 1 partition.

 

Hey Pirx, would love to read about your findings on the Momentus XT RAID0 tests as I want to get some faster HDDs for my Lenovo W700 to do faster editing on Premiere CS5 and I can also do a RAID setup. I'm afraid it might not be of any help to speed up editing though:

Adobe Forums: Seagate Momentus XT

 

thats an interesting thread there, animaitor.

this drive could help a lot, but it wont for 2 reasons. one is clearly that the NAND flash memory is only used when you read data, so it wont help for the actual changes written to files. the second reason is my opinion, i dont think the drives firmware is good for editing. seagate has left us with no choices as to how the 4gb is used, and i think it is probably collecting data over too long a period of time. so in other words, i think it is much more likely to get completely filled up with your program and boot files than to copy a huge chunk of raw video that you have been using for several hours straight.

essentially, its probably going to try and boost the speed of files used most often, not files used for single long periods of time.

 

I think you are right, niffcreature. It might be better to set it up as a system drive for the OS and programs.

 

I'd be very surprised if it did. Editing does not use the hard drive in any way, unless you're paging, in which case your performance will be down the drain anyway...

No, the hard drive doesn't have any concept of files, all it knows are logical blocks. So, what the drive will do, and all it can do, is cache the blocks that are read most often, using some metric that we can only speculate on. Ultimately, trying to guess the performance benefits of these drives for specific applications with nothing but the spec sheets to go on is an exercise in futility. Might as well read goat's entrails...

As for video editing, your best bet is lots of memory, and having write caching enabled on a hard drive with high sustained read and write performance. And, yes, the XT will never beat a decent SSD in that area. On the other hand, if you need lots of disk space and are not prepared to spend a couple grand on it, SSDs might not be your first choice. As always, it all depends.

 

ahh, well thats exactly what i didnt know about: paging. makes sense. i assume that happens when you run out of ram.

so if somehow you separated this disk and were able to control the two different drives, you would see a performance increase if you set the 4gb to you virtual memory.

how fast is that memory in there supposed to be anyway?

 

Paging happens even when you have plenty of RAM, depending on the application and resources it uses. Also you don't have control over what goes on the 4GB NAND memory (SSD). It's a read only cache managed by the drive controller to manage stuff off the HDD for quicker access.

 

OCC has a review of it in raid configuration.

 

wow so ur saying u can do RAID 0 and RAID 1 together lol? Any info on this? i completely alien to it.

 

See the help that comes installed with the Intel Matrix Manager software.

 

It isn't rocket science. Let's say you have two 500GB drives. Then let's say you split each into two partitions of 250GB. You install a Raid 1 volume across one partition from each drive, and a Raid 0 volume across the other partition from each drive. So you are left with a striped 500GB volume and a 250GB mirrored volume. Everything you need to keep safe gets mirrored and everything else goes on the striped volume for better performance. You would run into few performance losses since both volumes will very rarely be read or written to at the same time.

There is also Raid 0+1, but that would take 4 drives to function properly. In this case there would just be a mirror of a Raid 0 array.

 

Ive been looking into hybrid drives as of late, and I have to say, I'm very attracted.

SSDs are just to many $/GB, and I'd like a bit better performance with increased battery life, which I'd guess to be slightly improved by a hybrid, although I'd like to see it tested.

 

Yeah, I'm tempted to bite and get the Momentus XT just to see the difference.

 

Wikipedia RAID then look up RAID 0, RAID 1, RAID 0+1, RAID 1+0 and RAID 10. And yes, they are all different.