Raid - replacing a failed drive with a larger one; does it change the size of the array?

[dale_capetown]

Hi all

Wanting to rebuild my home system, thinking about a RAID 1 setup for the new machine.

I have a 500gb drive I would use to install my OS, but of course I need a second to build the raid. Was going to buy a 1tb - I know then that the array will only be 500gb and run at the speed of that 500gb disk, which is fine for Win and Program files for now; not looking for super hi-tech, I just want reliability and no downtime.

My question is, if that 500gb disk then fails and I then replace it with a second 1tb, will the raid grow or will it stick at 500gb? Any way to make it grow without reinstalling the OS?

Any insights would be appreciated. Raid is a bit of a black box to me, I'm afraid.

Thanks
-Dale

 

[dale_capetown]

The lab I work in uses Dell workstations with onboard Raid for some specialist hardware we run and they've been fantastic. Only 2 of the 9 machines have had a drive failure (easily fixed with Raid 1 anyway, just slot in a new disk and carry on) and we've never needed a system reinstall, knock on wood. The oldest one has been up for more than six years.

That may be because they're high-end Dell business machines, of course, not home-built ones put together by me! But I really thought Raid off the mobo was the way to go. Nevertheless I'll investigate an add-on raid card in the meantime, thanks for the advice.

 

[Solandri]

On-motherboard RAID is almost always software RAID. The "RAID hardware" is just a hook for the BIOS, so you can configure the array before the OS boots. Once the OS begins booting, it loads software drivers which handle the actual RAID functions.

An add-on RAID card is usually hardware RAID. This has the benefit of being faster and more robust than software RAID (though speed pretty much isn't an issue nowadays since processors have gotten a million times faster while HDDs have only gotten hundreds of times faster). But it has the downside of leaving you with no way to access your drives should the RAID card fail. Most companies which still use RAID cards buy 2 or 3 and keep the extras in the closet, so they can swap in a replacement if the first card fails. If a home user tries to be cheap and only buys one card, if it fails you may find that the card is no longer sold and you'll have no way to get your data back.

For this reason, I usually recommend software or on-motherboard RAID for home use. If that fails, all you need to do is transfer the drives to another computer with the same OS and RAID drivers, and you can read your data again.

You mention you are thinking about RAID-1. Please be aware that RAID is not a backup. RAID is for redundancy. If your company needs their file server to keep working even if a drive fails, then you want RAID. If you're thinking about using RAID-1 so you won't have to backup your drives as often, that won't work. If you accidentally delete or overwrite a file on RAID-1, it deletes or overwrites both copies simultaneously and there's no way to recover it. So even if you have RAID-1, you still need to make backups.

And for RAID-1, if you mixed a 500 GB and 1 TB drives, your RAID array would only be 500 GB in size. Depending on the RAID software, the remaining space on the 1 TB may be unusable, or you may be able to put a non-RAID partition on it. Replacing the 500 GB drive with a 1 TB after you've created the RAID array would not allow you to expand the size of the RAID-1 array above 500 GB. If you've got Windows 7/8 Pro or Ultimate, you should look into dynamic disks. It'll let you do the equivalent of RAID-1 (again, software RAID), but I believe it allows you to grow the size of the array after swapping disks.

 

[dale_capetown]

If a home user tries to be cheap and only buys one card, if it fails you may find that the card is no longer sold and you'll have no way to get your data back.

For this reason, I usually recommend software or on-motherboard RAID for home use. If that fails, all you need to do is transfer the drives to another computer with the same OS and RAID drivers, and you can read your data again.

Indeed I am trying to be cheap, thus only buyng a single 1tb and not two of them right off the bat. But thanks, I hadn't thought of what if the raid card fails.

You mention you are thinking about RAID-1. Please be aware that RAID is not a backup. RAID is for redundancy. If your company needs their file server to keep working even if a drive fails, then you want RAID. If you're thinking about using RAID-1 so you won't have to backup your drives as often, that won't work. If you accidentally delete or overwrite a file on RAID-1, it deletes or overwrites both copies simultaneously and there's no way to recover it. So even if you have RAID-1, you still need to make backups.

And for RAID-1, if you mixed a 500 GB and 1 TB drives, your RAID array would only be 500 GB in size. Depending on the RAID software, the remaining space on the 1 TB may be unusable, or you may be able to put a non-RAID partition on it. Replacing the 500 GB drive with a 1 TB after you've created the RAID array would not allow you to expand the size of the RAID-1 array above 500 GB. If you've got Windows 7/8 Pro or Ultimate, you should look into dynamic disks. It'll let you do the equivalent of RAID-1 (again, software RAID), but I believe it allows you to grow the size of the array after swapping disks.

I do know Raid isn't a backup system and I'd still need to do manual backups, my concern is a failed unrecoverable primary/OS disk which prevents me from getting something I want or need and requires a full OS reinstall, which is such a hassle. I'll read up on dynamic disks; that may be a better option in the end.

Thanks for the advice.

 

[FireWire2]

Hi all

Wanting to rebuild my home system, thinking about a RAID 1 setup for the new machine.

I have a 500gb drive I would use to install my OS, but of course I need a second to build the raid. Was going to buy a 1tb - I know then that the array will only be 500gb and run at the speed of that 500gb disk, which is fine for Win and Program files for now; not looking for super hi-tech, I just want reliability and no downtime.

My question is, if that 500gb disk then fails and I then replace it with a second 1tb, will the raid grow or will it stick at 500gb? Any way to make it grow without reinstalling the OS?

Any insights would be appreciated. Raid is a bit of a black box to me, I'm afraid.

Thanks
-Dale

Here are things I would do:
- Get a SSD 60~120GB set is as OS, transfer or fresh install
- Create a RAID1 from 500 and 1TB. Note: 500GB of 1TB won be accessible,
You can grow your RAID in events:
500GB failed, or desire to have a bigger storage. <-- this requires another post 🙂

Yes is the answer to your question "Any way to make it grow without reinstalling the OS?"