A few questions regarding RAID 0

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Marin85 · #1 Post by **Marin85** » Tue Jun 10, 2008 5:29 pm

Hi,
I would like to obtain a second Hitachi 7Kxx and then configure performance RAID 0 system in my ThinkPad, so:

1. Do HDDs have to be of the same type and size?
2. Would the ultrabay HDD be then still hot-swappable?
3. Is it possible to configure RAID 0 only between some sets of partitions on both HDDs (i.e. my primer HDD has partitions A and B, my ultrabay HDD has partitions C and D -> RAID 0 between A and C

)?
4. In what way does RAID 0 provide higher transfer rates (e.g. redundant writing and then simultanous reading or distributing different data between the RAID HDDs for simultanous reading of different data)?
5. What could I expect from my TP in terms of "one-big-HDD"-performance increase?

6. Do I have to reinstall OS and apps in order to set up RAID 0?
7. Does RAID allow dual boot?
8. Is it possible to boot from an ultrabay HDD?
9. What are transfer rates of ultrabay HDDs limitted to?

The background: I´m planning on upgrading my TP with a second HDD, so I´d like to find out what configuration would fit to my needs best. Thanks in advance and sorry for the quite brief overview

Marin

#2 Post by **Kyocera** » Tue Jun 10, 2008 5:48 pm

http://lenovo.vo.llnwd.net/o16/TechBrie ... layer.html

I have not read of anyone trying to do what you are on a laptop. But the above link gives you all the real information about RAID, I have watched these videos a few months ago and specifically this RAID video was almost to in depth but then RAID is pretty complex. You can go straight to the RAID 0 video, but I suggest watching them from the beginning as this will answer your questions about the performance issues with raid configurations.

#3 Post by **erik** » Tue Jun 10, 2008 6:40 pm

marin - first and foremost, what do you plan to use as a RAID controller? thinkpads don't have hardware RAID controllers.

given that, i can only answer your questions in a hypothetical manner since there's no way to do hardware RAID 0 on a thinkpad.

1. no.
2. no.
3. no.
4. transfer rates are increased due to simultaneous reads/writes being striped across two drives, plus RAID 0 doesn't have fault tolerance or redundancy to slow the array down.
5. 30% on average.
6. yes.
7. yes.
8. yes.
9. 100Mbps in theory.

#4 Post by **Kyocera** » Tue Jun 10, 2008 6:47 pm

#1 is no - at least according to what I have read regarding raid 0 you are limited to the size of the smallest drive.

#3 ? i have read of partitioning schemes for Raid 0

Marin85 · #5 Post by **Marin85** » Tue Jun 10, 2008 6:51 pm

I was thinking the whole time that ThinkPads have built-in RAID controllers

Erik, that was a shock for me

I guess I now have to give up my idea of running RAID in a ThinkPad

Still, there is one question left: who was the guy that told me ThinkPads have RAID controllers

Well, I think I should at least apologize for the very silly thread started by me!

Cheers

Marin

EDIT: And last but not least Thanks to erik and Kyocera for your very straightforward and real-time replies!

#6 Post by **gator** » Tue Jun 10, 2008 7:00 pm

Not just thinkpads, I don't think there are any laptops out today with a built in RAID controller ... correct me if I am wrong.

#7 Post by **erik** » Tue Jun 10, 2008 7:37 pm

Kyocera wrote:#1 is no - at least according to what I have read regarding raid 0 you are limited to the size of the smallest drive.

#3 ? i have read of partitioning schemes for Raid 0

regarding #1, mismatched drives (both in speed and size) are possible. i wasn't paying attention and should have answered 'no' to this.

regarding #3, it is possible to partition the array but i don't believe that specific partitions can be striped—and that's what marin seems to be asking about.

gator wrote:Not just thinkpads, I don't think there are any laptops out today with a built in RAID controller ... correct me if I am wrong.

alienware might have notebooks with hardware RAID but i must admit that it's been ages since i last looked into this.

Marin85 · #8 Post by **Marin85** » Tue Jun 10, 2008 7:42 pm

AFAIK there are a few notebooks with RAID controllers: Eurocom for sure, Alienware probabely too as erik pointed out, Dell XPS (M1730 for sure) and similiar...

Cheers

Marin

Marin85 · #9 Post by **Marin85** » Tue Jun 10, 2008 8:17 pm

Correct of I´m wrong, but despite the absence of hardware RAID controller in ThinkPads one is still able to set up a Software-RAID

The question is of course if that makes much sence since this increases the cpu load. Anyone with software-RAID here to comment on?

Marin

#10 Post by **erik** » Tue Jun 10, 2008 10:03 pm

software RAID would have a lot of overhead, minimizing most or all of the performance benefits of non-parity striping. if you can't do hardware RAID then i wouldn't do it at all.

Marin85 · #11 Post by **Marin85** » Tue Jun 10, 2008 10:36 pm

Then the question is still how to set up hardware RAID with two internal HDDs. My Z61p has a slot for ExpressCard or Type I or II PC Card.There might be anything like RAID controller Express Card...

Marin

EDIT: Are there any other free internal slots like mini PCI-E etc (which in my case is occupied by an Intel wifi card)?

EDIT 2: ExpressCard adapters would only connect to external drives (at least what my logic tells me). There is probabely no way to "redirect" transfer to an ExpressCard adapter from internal HDDs and then to the cpu.

graywolf · #12 Post by **graywolf** » Sun Jun 15, 2008 3:49 pm

You could set up a software raid.

BUT!!!! You could not use your Thinkpad off the Ultrabay.

I have read of folks attempting to setup RAID-0 with 2 compact flash cards on an IDE adapter as a solid state drive. The reports were that it was not very reliable.

So even if you do not mind having to leave it on the UB it still seems not to be a very practical idea.

beeblebrox · #13 Post by **beeblebrox** » Thu Jun 19, 2008 12:14 pm

As far as I know from well informed sources there is one Thinkpad that can be configured in a RAID:

It will be the W700, which will have 2 built-in HDDs. In addition with the new mobile quad cores.
The W-Series is supposed to come out around October/November I remember...

On other thinkpads you can use only software RAIDs, not so useful.

Marin85 · #14 Post by **Marin85** » Thu Jun 19, 2008 3:44 pm

Thanks for your replies! I have almost forgotten this thread

As to the CFs I too don´t believe it would deliver any significantly better performance than my current Hitachi 7K200 does.
I was also thinking of setting up software RAID just out of curiosity

, but all I found out was that one has to convert his disks to dynamic disks, however this feature is not supported for mobile computers. In the mean time I had the opportunity to try out Server 2008 but neither it would let me convert to dynamic volumes. That said, I would appreciate it if someone could post some guide or info or some links as to how to set up software RAID 0 under Vista (with respect to the restrictions above).
Thanks again for your replies!

Cheers

Marin

A few questions regarding RAID 0

A few questions regarding RAID 0

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