RAID50?

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Sovereign

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I have a PERC5/i with a 6TB (4TB usable--RAID5). It supports RAID50.

I know what RAID50 is (RAID0 striped over two or more RAID5 sets).

Normally RAID0 is bad (no fault tolerance) but a RAID50 array can sustain a single disk failure in each array since each "RAID0" component is actually a single-fault tolerant array.

So the question is, is there any reason not to use RAID50 when I inevitably buy more drives instead of having two separate RAID5 arrays from a data integrity/fault tolerance perspective?
 
Depends. I've found raid 50 works well, but you still have to keep a tight watch on the drives - lose one entire raid 5 cluster and you are up the creek.

When I've got that many drives, I tend to stick with raid 10. Multiple mirrored stripes has the advantage that having 2 of the same drives in a mirror die together are slim.

You are using drives from different manufacturer batches, right?
 
Doward said:
Depends. I've found raid 50 works well, but you still have to keep a tight watch on the drives - lose one entire raid 5 cluster and you are up the creek.

When I've got that many drives, I tend to stick with raid 10. Multiple mirrored stripes has the advantage that having 2 of the same drives in a mirror die together are slim.

You are using drives from different manufacturer batches, right?
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I have three Samsung SpinPoints, but those are discontinued and must be bought on eBay. I have no idea which batch they were from, though I did order them all at the same time from NewEgg.

The next question becomes (regardless of chosen RAID level), will there be issues with mixing in other manufacturers' products? And what should I use? (Desired capacity: 2TB/drive.)

I was looking at WD Reds, but they seem (based solely on NewEgg reviews) to be hit-or-miss.
 
Everything with newegg is hit or miss.

By which I mean either they hit it with a bat as it's rolling down the conveyor belt to the truck or they miss.

Check the WD Red reviews on amazon, far fewer (like 70-80% fewer) DoA's probably several of those are from 3rd party vendors, I saw at least one 1 star that mentioned a 3rd party in the title.

Buying at newegg to save a few bucks is like paying full price and them paying you a few bucks to play "break the piñata" with your shit before they send it out.
 
Meh, I don't want to get into a debate about NewEgg. While they may not have the sterling reputation they had when I started shopping with them 12 years ago, they have *never* done wrong by me.

I've often mixed drives from different manufacturers. Try to keep them spec'd the same though - 7200rpm, 16MB cache, etc.

I purposely mix drives of different manufacturers, and manufacturing dates. Don't want to have multiple drive failures!

Your raid array will always run as fast as your slowest hard drive. You can stripe raid a 500GB SSD to a 500GB HDD, and you'll perform like 2 500GB HDDs, simply because your SSD got its data out super fast, but is having to wait on the HDD to catch up.
 
-Dragon- said:
Everything with newegg is hit or miss.

By which I mean either they hit it with a bat as it's rolling down the conveyor belt to the truck or they miss.

Check the WD Red reviews on amazon, far fewer (like 70-80% fewer) DoA's probably several of those are from 3rd party vendors, I saw at least one 1 star that mentioned a 3rd party in the title.

Buying at newegg to save a few bucks is like paying full price and them paying you a few bucks to play "break the piñata" with your shit before they send it out.
Click to expand...

I have only ever had 1 drive DOA from newegg
 
You can mix drives in RAID as long as every drive you use is supported. You can mix brands, series, RPM, etc. But if you had say an array of 15KRPM disks, adding in a single 7200RPM disk would slow the entire array down somewhat. I do recommend mixing brands and/or buying your disks from different batches to lessen the chance of multiple disks failing in a short period of time.

When running RAID-10, 50, 60, etc. you do add extra fault tolerance to a degree, but keep in mind that while more disks can fail, it's only safe if certain disks fail. For example, I have a 4-drive RAID-10 (well, the ZFS equivalent, 2 mirrored vdevs in a pool) and I can lose "up to" 2 disks. If I lose 1 disk from each mirror, fine. But if I lose 2 drives in one mirror, I'm screwed. Compare this to RAID-6 (RAID-Z2, whatever) which for 4 drives would give me the same capacity, but I could then lose any 2 disks and still be okay. But performance for RAID-Z2 would be worse.
 
dandragonrage said:
You can mix drives in RAID as long as every drive you use is supported. You can mix brands, series, RPM, etc. But if you had say an array of 15KRPM disks, adding in a single 7200RPM disk would slow the entire array down somewhat. I do recommend mixing brands and/or buying your disks from different batches to lessen the chance of multiple disks failing in a short period of time.

When running RAID-10, 50, 60, etc. you do add extra fault tolerance to a degree, but keep in mind that while more disks can fail, it's only safe if certain disks fail. For example, I have a 4-drive RAID-10 (well, the ZFS equivalent, 2 mirrored vdevs in a pool) and I can lose "up to" 2 disks. If I lose 1 disk from each mirror, fine. But if I lose 2 drives in one mirror, I'm screwed. Compare this to RAID-6 (RAID-Z2, whatever) which for 4 drives would give me the same capacity, but I could then lose any 2 disks and still be okay. But performance for RAID-Z2 would be worse.
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I guess it sounds like two four-disk RAID5 would be better then--because if one disk in either array fails, I can keep the other array online (instead of RAID50 where if one drive in one array fails, the other half's fate is now tied to the first).
 
You can also grow the RAID5, go RAID6...

Backups are key.
 
Aesma said:
You can also grow the RAID5, go RAID6...

Backups are key.
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Card doesn't do RAID6. I'm under the impression that having more drives in RAID5 is increasing the likelihood of a two-drive failure.

I have an unlimited Backblaze plan, just no upstream to actually finish the job...
 
perc 5/i can be picky about drives. tread carefully. I'd suggest getting a full backup plan in place, or creating a new system and "expanding" by replacing your primary file server with it.

two systems with no redundancy is much better than a single system with, IMO.
 
dandragonrage said:
You can mix drives in RAID as long as every drive you use is supported. You can mix brands, series, RPM, etc. But if you had say an array of 15KRPM disks, adding in a single 7200RPM disk would slow the entire array down somewhat. I do recommend mixing brands and/or buying your disks from different batches to lessen the chance of multiple disks failing in a short period of time.
Click to expand...

I would never recommend mixing drives from different manu's. And I would recommend against mixing drives of any differing attribute ever. It's like asking for a disaster. Especially on a PERC.

A PERC 5/i will top out at 5-600MB/s anyway. It's proc can't handle more.
RAID50 if you want a big pool and watch (as someone said above) closely for failures. If you have a SAS expander or extra ports, have a hot-swap ready.
Dual RAID5's if you don't care about combining for a big pool, you can always do something in software (sym-link, junctions etc)

Tx,
JM
 
terayon1515 said:
I would never recommend mixing drives from different manu's. And I would recommend against mixing drives of any differing attribute ever. It's like asking for a disaster. Especially on a PERC.
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You would be incorrect, because RAID controllers/HBAs do not judge the characteristics of one drive based on those of the other drives, period. It only judges the drives based on specifications of the SATA/SAS protocols and the card itself. With SATA/SAS they are all on separate channels. Your concern is valid on older shared-bus setups like SCSI and IDE, but is just paranoia today. Back up your info otherwise and do let us know why/how one drive will affect a different drive on a different channel (if you can, I would honestly like to know). Lots of people recommend against doing stuff just because.

I do agree that the Perc5 isn't a particularly good card, but it doesn't matter.
 
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