RAID 5 or 10 for shared VIDEO?

[Caspian Brand]

I’ve set up a lot of video RAIDs in my day, and with RAID 5 I do not like to create a Logical Volume larger than 12 physical disks, and then only when a Hot Spare is configured. The magic number of disks for most video (for the exception of some Uncompressed HD formats) is 6 – 8 drive members. If you have a 16 Bay array I would recommend two 8 disk RAID 5s. If you have a 12 Bay array I would recommend two 6 disk RAID 5s. As Bob mentioned, RAID 5 is the best for video. If you want more physical drives and one larger volume, then you can use your server to create a RAID 0 stripe across multiple RAID 5 logical volumes (also known as RAID 5+0 or RAID 50). This approach keeps your ratio of redundant drives reasonable, while increasing the total number of disks in play for performance. The downside is what can happen if your Server looses it’s RAID 0 striping information.

RAID 10 is a good solution for a Nearline Archive, which you may want to consider for your second enclosure.
Or if you have a Quad port HBA, you can RAID 50 across both controllers using four RAID 5 volumes.

In short, your safest bet is multiple RAID 5 volumes for video, and possibly a separate RAID 10 array for Nearline. Make sure your server is maxed out on RAM if your clients are funneling through network shares to the storage.

Depending on how much realtime work you end up doing you may outgrow the approach of a Server with Direct Attached storage. At such time you may need to opt for a high performance NAS or SAN.

[Bob Zelin]

Caspian writes –

I’ve set up a lot of video RAIDs in my day, and with RAID 5 I do not like to create a Logical Volume larger than 12 physical disks, and then only when a Hot Spare is configured. The magic number of disks for most video (for the exception of some Uncompressed HD formats) is 6 – 8 drive members. If you have a 16 Bay array I would recommend two 8 disk RAID 5s. If you have a 12 Bay array I would recommend two 6 disk RAID 5s. As Bob mentioned, RAID 5 is the best for video. If you want more physical drives and one larger volume, then you can use your server to create a RAID 0 stripe across multiple RAID 5 logical volumes (also known as RAID 5+0 or RAID 50). This approach keeps your ratio of redundant drives reasonable, while increasing the total number of disks in play for performance. The downside is what can happen if your Server looses it’s RAID 0 striping information.

REPLY – damn Caspian – do you work for me ? This is exactly what I do. I split large array boxes into two RAID 5 arrays, just as you have suggested here. And for those that insist on a single 16 drive array – well, that is exactly what RAID 6 is for. When you look for trouble, you have to protect yourself.

Bob Zelin

[Neil Sadwelkar]

This discussion on RAID types, beginning with a user finding a spare RAID at the back of his closet, makes me wonder on one aspect of RAID. Safety.

I’ve been through various RAID types and solutions. And I’ve been through disaster. When drives fail. And the temporary loss of data. The nerve wracking hours when the RAID is rebuilding after a drive replacement.

RAID 1 is a mirror, but if one drive/volume fails, you can’t get access on the good one till you rebuild the whole RAID.

So how about this? Let your RAID 10 remain as it is. So your facility has no down time.
Then configure the new empty one as RAID 5. Place it on the network and have some backup utility backup files daily or at regular intervals. Not compressed, and with the exact same folder structure. So you effectively have a mirror, but a working mirror.

Then if your main RAID 10 fails, you simply have to access the mirror which is current. And in the background rebuild and fix the bust RAID 10.

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Neil Sadwelkar
neilsadwelkar.blogspot.com
FCP Editor, Edit systems consultant
Mumbai India

[Mike Renner]

I wanted to respond to this aging thread with the following.
I have done some video work with striping on a local disk and this is great for performance (for the day).
The issue with RAID is getting ugly. I have heard there is more risk of using 1TB+ drives on raid 5 configuration due to the possibility of unrecoverable read error rate (URE) of 10^14 (many drives today) causing a URE when rebuilding a raid 5 setup. If this were to occur while rebuilding you are done, your data is gone. This is why RAID6 is being pushed harder to deal with 2 disk failures with the now poor URE of modern sata drives; not great for video, but you can backup your daily edits from local striped drive RAID 0.

Comments are welcome as this whole RAID question is causing me grief right now.

Please see:
https://blogs.zdnet.com/storage/?p=162

Thanks,
Mike Renner

[Vince Becquiot]

I think it really depends on how many people are working on the particular system and the budget you’re after.

I find that a RAID 0 is perfect for us and much more affordable than anything else. It uses the least amount of drives for the size, and can be setup starting at around $500.00 including case and drives.

In our case, the only thing that needs to be on the array is HD captured and rendered uncompressed footage, things that we already have on tape or other drives from capture time, so even in the event of a catastrophic failure (Which can happens on RAID 5 too), we still have a copy.

It is backed up every few hours through ViceVersa to a standalone box without any noticeable degradations while the mirror backup is being performed, which usually only takes minutes anyway.

Vince Becquiot

Kaptis Studios
San Francisco – Bay Area