RAID on T61p

[haritak]

For the last 6 months I am running my Linux on RAID10 using two HDDs.
Moreover, the last three months are on an updated BIOS (http://forum.notebookreview.com/lenovo- ... ost6501443).
Upto now all run smoothly. (My laptop has an 99% uptime, constantly on, rarely rebooted)
You can find more details on my blog (http://ych.me/?cat=8 - don't rush, the server is only a vm with 256MB RAM )

Here are some more info:
I use two HDDs one internal and one on the ultrabay :
* WDC WD5000BEKT-22KA9T0
* ST9500420AS

I started with raid0 - stripping. That was a rather addictive experience! Fast and huge space 1GB in total!

However, since I code some times, and I do keep my photos on my laptop for quite a long before backing them up, I was feeling rather insecure.
So I reverted to raid1 - mirroring. 500GB and a little performance penalty on the "writes".

However, the experience from using raid0 couldn't leave me in peace!
So, I tried raid10 and I plan to stick to that.

Any ideas, how to add another hdd ??

[TuuS]

My understanding is that the ultrabay drive cannot even use sata1, so I think you'd be better off using an ssd as primary, and perhaps a 1tb in ultrabay as a backup and for storage.

I'm doing something similar with mine, but since I already have a 750gb, I'll use that in ultrabay and an Intel 320 series ssd as primary.

This is on my T61p with T9300


Similar setup on my w510 with i7 quad core

[ac12]

With RAID 10 or 0+1 (stripe+mirror), as I understand it, you need a min of 4 drives.
To stripe you need a min of 2 drives, then double it for the mirror
2 drives (stripe) * 2 (the mirror) = 4 drives total

So, I can't see how you are doing RAID 10 with only 2 drives.

I recommend that you periodically backup the drive to an external USB or FW drive.
This is better than relying on a mirrored drive for backup. A mirror will not protect your data from things like accidental deletion.

[haritak]

My understanding is that the ultrabay drive cannot even use sata1, so I think you'd be better off using an ssd as primary, and perhaps a 1tb in ultrabay as a backup and for storage.

Well, I hardly remember long time ago performing some performance tests and confirming that there is indeed a performance penalty using the ultrabay. I can't recall however how much was that. (I use palimpsest under linux. Nothing special, gives a hint on the performance). It is one reason I did the BIOS upgrade. However, I
haven't checked whether the difference persists or not.

The nice thing about setting up a raid is that it is an "online" backup. If something goes wrong on one disk you can just replace it and keep working
while the raid is being restored. Zero time lost on recovery. This is confirmed.
On the other hand, if some files are backuped elsewhere you still need to reinstall the universe when the primary disk goes down. I am using the same linux 5 years know,
there is no way I can build it and configure it again in less than a month!

I believe SSDs must be quite reliable, but still I can't have the same peace of mind.

Regarding 1gb HDDs, as far as I know, they are a little bit more thick, and they don't fit in the ultrabay, nor inside. Am I wrong ?

I'm doing something similar with mine, but since I already have a 750gb, I'll use that in ultrabay and an Intel 320 series ssd as primary.

This is on my T61p with T9300


Similar setup on my w510 with i7 quad core

My next disk upgrade will be two SSDs on raid10. That will be my present next Christmas ...

[haritak]

With RAID 10 or 0+1 (stripe+mirror), as I understand it, you need a min of 4 drives.
To stripe you need a min of 2 drives, then double it for the mirror
2 drives (stripe) * 2 (the mirror) = 4 drives total

So, I can't see how you are doing RAID 10 with only 2 drives.

I recommend that you periodically backup the drive to an external USB or FW drive.
This is better than relying on a mirrored drive for backup. A mirror will not protect your data from things like accidental deletion.

Pardon me for the misleading information! While creating the array, I did indicate I want a raid10 with 2 disks, which the tools (mdadm) do allow, this will end up
in a slightly different raid1 configuration.

The difference is that each disk is not exactly a mirror of the other. The data are completely the same (as in raid1) but the layout of the data on the disks is different (which differs from raid1).

Since each chunk of data is replicated, the different layout aims at having one of the two chunks on the outer side of the disk always.
That's why you get a flat read performance across all disk capacity.

So it's not a raid10, and it's not a raid1.

Thanks for helping me clarify this point!


PS:
It's ok if these sound greek to you.

[ac12]

Interesting, that RAID configuration is something I did not know about. Learn something new every day.