painintheuk

I just found this: http://www.zdnet.com/blog/bott/windo...tag=rbxccnbzd1. The link at the bottom to Part 2 has some details on optimizing (including dealing with TRIM).

Dr. PITUK

Landing Gear

In further perusing the Sony website, I found this option for the Z series laptop:


What does "256x2" mean? Is this two separate drives, e.g. C and D drives?

What does "RAID 0 Technology" mean? Or does this require a separate thread?

Loren Pechtel

What that means is that you actually have two hard drives, each of which holds 256gb. The motherboard understands that they are to be operated as a pair, one chunk comes from the first drive, then the next comes from the second drive, back and forth as you go. You see it as a single 512gb drive.

This increases the speed at the expense of reliability as a failure of either drive renders the data on the other useless. A bit reckless for normal hard drives but SSDs are reliable enough that it's a reasonable thing to do. (And the best of the SSDs have been doing this internally anyway.)

nkedel

Given the RAID 0 part, I assume that means two physically-separate drives which appear as a drive to the operating system (and thus one drive letter, unless you choose to partition it) with the capacity of the two combined, and with writes/reads striped across the two - if you read the first nkb/mb of data, it will read [n/2]kb/mb of data from each in some-size chunks (typically 64k or 128k) so for reading/writing large amount of sequential data it will be nearly twice as fast. Two SSDs in a RAID0 are going to be very, very fast indeed for sequential reads, probably beyond what's useful for anyone in a laptop, but the faster writes will be good for some things.

RAID 0 is one of the two simplest sorts; RAID1 (mirroring) means you have a full copy of everything on each drive (thus the total capacity is the same as either drive rather than the total of both) and you can have one drive crashed/removed without losing data (or in some cases even having to stop what you're doing/reboot/etc)

http://en.wikipedia.org/wiki/RAID if you want to know more.

Landing Gear

Thank you both. Still a bit confusing and I did look at Wikipedia but it's somewhat too technical.

In a set up such as is on the Z laptop, would the programs be on one drive and the data on the other? Or do you have no choice as to where they go?

Is it possible that, for example, the contents of the My Documents folder could be distributed between the two drives.

What happens if one drive fails?

trueblu

RAID 0 technology has the disadvantage, as stated above, that if one drive fails, both fail -- i.e. catastrophic failure (to my understanding), but also as stated, the failure rate is low.

What I would like to know is with a set-up such as this, is there any value in partitioning the drive?

tb

Loren Pechtel

You get no choice. Everything is split between the two drives. It's not even on a file-by-file level, but even lower level. The only time I've set up a Raid 0 (actually, a Raid 10 which uses 4 drives and gives reasonable safety, but it configures rather like a Raid 0) it used 64k stripes. 64k of data to one, the next 64k to the other, independent of the file structure.

If you lose one drive the data on the other is worthless.

Landing Gear

This is just getting better and better.

How would you back up a system like this on an external hard drive?

Better yet, how would you restore to a system like this?

nkedel

Loren has already answered thes, but to reiterate in other words: yes, you have no choice as to where they go. It looks like one big drive, and any files larger than the stripe size will be split across both disks. (Files smaller than the stripe size may or may not be.)

It will inevitably be that way. On the other hand, to a user it will all lool like it's on the same drive, and there's no reason to worry about what's on which.

Data gone, better have a backup.

Not for most people (of course, I'd generally say that these days with any kind of drive, with or without RAID). If may have value:
* if it's helpful to you for organization or segregating space, or
* if you're dual-booting, or
* if you're doing certain kinds of work where two different file systems (or in Windows, two different cluster sizes for NTFS) are valuable

The same way as you would any other drive, either by backing up the files or by creating a disk image. As far as the files are concerned, it's one big file system (drive C: or / or whatever) and as far as the disk image is concerned, it's one big disk (the physical location of the blocks on two - or more - disks is invisible and irrelevant as far as either operation is concerned.)

You set up the driver (or the software RAID) in Windows (or whatever OS) before doing the restore. Other than that bit of setup (which may be automatic, depending on the hardware and OS) It's no different restoring a 512GB RAID array than it is restoring a comparable size single disk - the RAID looks like one big disk at a level below that of the file system, and before installing/restoring, if you've ever looked at the UI to do partitioning, in most cases it would look like one big unformatted disk in that UI.

It is, for example, no problem to back up data from a RAID setup and restore that onto a single disk, or vice versa (indeed, I've done so recently with a friend: when his hard drive failed, I helped him set up a RAID1 [mirrored drives] and then restore his backups onto it.)

swanscn

A Raid 0 disk is seen as a single drive and single drive letter to the OS. In this case it would most likely be seen as the "C" drive. Your external disk would also get a drive letter maybe "E" with the "D" drive being the bluray drive. You would then backup the "C" drive to the "E" drive in this example.

I am not a fan a of Raid 0 technology by combing 2 disks into 1 is not a risk I am willing to take. As other have correctly stated a problem on one drive is a problem for the other as well. If you have these running as 2 drives instead of 1 a failure of 1 would not cause data loss on the other.

This is one of those time of "Just becasue you can do something, doesn't mean you should"

swanscn

I took a look at the Z series and found what you did, they do not offer a non Raid 0 setup. For me this would be a deal breaker.

Loren Pechtel

It looks just like an ordinary hard drive, anything that could back up an ordinary hard drive could back up a pair like this.

While I have never run Raid 0 I have run arrays in levels 1, 5 and 10. All look just like an ordinary drive even to drive copying tools. Without either a detailed look in device manager (and the knowledge to know what it's describing) or opening the case you wouldn't realize it's really an array (barring the giveaway of a reported drive size in excess of anything on the market.)

nkedel

Depends on what you're using it for; it's great for temporary working space, or for application/OS installations which you can reinstall if you've got a separate non-raid volume for data. For that matter, if you've got a decent backup, it's not a bad way to get extra speed - one big slow drive plus two smaller fast ones and automated backup is often cheaper than 4 faster ones (for a RAID 10 - striping + mirroring.)

Ditto if your important data is already on severs; until we moved to SSDs, the default configuration for developer machines at my workplace was dual 15k SAS drives. The assumption is that anything really important that's more than a day or two old is in source control or on a file server.

jrpaguia

RAID 0 with SSDs are actually quite clever...again, there are no moving parts. I don't see where it is more probable for one of a pair of drives to fail than it is for your one and only drive to fail.

The vast majority of laptops in use today have one single drive (with a bunch of moving parts) and we don't see all of them falling out of the sky, so to speak.