RAID considerations

[stiltman]

Just go RAID5 and be done with it

[rallynavvie]

It sounds like RAID 5 with a hot spare is probably the way to go with the hardware I have. I had almost all but decided on RAID 10 when I posted but between here and some of the engineers at work the other option is going to give good performance, better drive utilization, and still retain the redundancy (just in a different matter). I'll post some before/after later.

[rallynavvie]

Finally got the drives in and started putting things together. I don't have time to take down my workstation and install this quite yet but maybe tomorrow or over the weekend. I don't really enjoy re-imaging my machine but it's been running for over a year so it wouldn't hurt to start over with a clean install.

I had to get right-angle adapters for the SATA connections on the backplane so I could use the SFF-8087 cable for the controller. The big heatsink on the controller is a northbridge heatsink to help cool the dual-core processor that lives on that controller. Apparently that chip runs really hot and the stock heatsink doesn't keep up.

This is the drive cage, controller, and drives with the drive "handles" on them for the backplane:


Here they are tucked away inside the backplane:

[lordsmurf]

The only RAID that I do is RAID1 on some working drives. It's an "instant backup" for drive hardware fails, should one happen. Not a bullet-proof backup for all fail scenarios, but good enough to fight the problems I have had historically.

RAID0 screws up drives. To even call it "RAID" is a misnomer.

RAID5+1 is probably my favorite. Needs 6 drives, though.

[rallynavvie]

The only RAID that I do is RAID1 on some working drives. It's an "instant backup" for drive hardware fails, should one happen. Not a bullet-proof backup for all fail scenarios, but good enough to fight the problems I have had historically.

RAID0 screws up drives. To even call it "RAID" is a misnomer.

RAID5+1 is probably my favorite. Needs 6 drives, though.

I used RAID 1 when I was running my video business for the main storage drive so that I could have a backup of it should the one fail. As they filled up I would replace it with a similar size drive (was using 250GB drives at the time), clear the array, and start over. The full drive was kept at a "data storage facility".

If you had read the thread I don't condone RAID 0 for anything other than scratch space. I changed my mind on this project and decided to run 4-disk RAID 5 since I can get a replacement drive cross-shipped in a few days and the degraded performance of the remaining 3 disks is still better than a single drive. I can live with that. The other options were to use 3-disk RAID 5E (the 4th is the hotspare) or a basic RAID 10. Since this is OS/apps volume I would rather have the better read performance of the option I chose instead of the faster write access of RAID 10. Looking at drive activity there aren't a great amount of writes to the OS/apps volume.

[edDV]

RAID 1 is not a true "backup". It will protect you from a drive failure but not file corruption or human error which modifies both copies. You still need a separate backup to go back in time should such errors occur.

[rallynavvie]

I used RAID 1 when I was running my video business for the main storage drive so that I could have a backup of it should the one fail.

Like I said, the idea was a backup should a drive fail. For that particular drive it only consisted of final DVD ISOs so there wasn't much chance of simple data corruption as the build had already been tested prior to migrating it to the storage volume. In-flight projects were backed up using nightlies.

[rallynavvie]

I hate my luck with putting computers together. My own never seem to go according to plan

So I tried installing the drive bay this afternoon and the fan on the back of the drive cage runs right into the EPS12V 8-pin connector on the leading edge of the board. Now I had figured it would be a tight fit but since both my case and the drive bay are both Lian Li and both use the same design that they would have checked to make sure this drive cage would fit on their cases (of like design) with an EATX board. Furthering this point is the fact that most users of this hot-swap-capable SATA backplane would be using a workstation-class system with, likely, an EATX board. But this is not the case, and further irritating is the fact that the fan is offset towards the board instead of away from it. I might be able to modify the cage itself to shift the fan to the other side but I hate cutting apart such an otherwise well-built component.

The other option is to run four 10krpm Raptors without any airflow over them except what the 120mm exhaust fan is pulling through the case. At least the HDDs would be on the leading edge of that cool air, but from the looks of the drive spacing above I don't think that would be wise?

Alternatively I could rout cables outside my case and run the drive cage out in the open

[rallynavvie]

Pulled the fan off to see if case airflow would be enough. Unfortunately I haven't found an app that can monitor the HDD temps past the controller so I'm still searching. Since they're going to be idle and unused for now they should be fine.

HD Tach read an average of about 170 MB/s sequential read with a 769 MB/s burst. The short test showed much higher results of 300 MB/s. Everest tested sequential write speeds averaged 230 MB/s. Should make a great OS/application volume since average seek times are still down around 5ms.

Taking the fan assembly to a fab shop to see if they can rig something up that will fit on the back of the drive cage. Once that's in place I will re-install and start fresh.

[ocgw]

Pulled the fan off to see if case airflow would be enough. Unfortunately I haven't found an app that can monitor the HDD temps past the controller so I'm still searching. Since they're going to be idle and unused for now they should be fine.

HD Tach read an average of about 170 MB/s sequential read with a 769 MB/s burst. The short test showed much higher results of 300 MB/s. Everest tested sequential write speeds averaged 230 MB/s. Should make a great OS/application volume since average seek times are still down around 5ms.

Taking the fan assembly to a fab shop to see if they can rig something up that will fit on the back of the drive cage. Once that's in place I will re-install and start fresh.

Seriously nice i/o performance rallynavvie

ocgw

peace

[rallynavvie]

I completed my tests a couple days ago and loaded up a fresh install of Vista on the new array to begin the transition from my single boot drive. Despite those who claim faster Windows boot times as a benchmark for RAID I have seen my boot times increase dramatically. The reason is obvious (and I'll let you smart folks guess what that is), I just never really thought about it until I was doing a bunch of reboots while installing updates

The read performance combined with the seek times of the 10krpm drives did well in some of my tests, one of which was installing BF2 to that volume and watching load times of the really large maps. I also moved a few of my resource hog VMs over to that volume to see how well they performed. Using two VMs simultaneously on that volume showed a significant performance increase over running them simultaneously on a single 7200rpm drive.

I mitigated the heat issue with the drives by customizing the backplane fan to fit around my EPS12V connector. They're running comfortably now. The handles on them act like heatsinks which may have been a design feature of the backplane (+1 for Lian Li). The controller still runs ridiculously hot, sometimes reaching 92C even with that big heatsink on it. Funny thing is it still states it's operating within "Normal" temps. I'm going to put a 40mm chipset fan on the side of the heatsink to cool it down, I've got one which makes almost no noise.

As to the noise I was somewhat surprised that four Raptors do not make 4x the noise of a single one. The HDD access noise is completely tolerable even with this being a quiet HTPC build. And yes, you'd be surprised what really good case design and a little effort can do to keep a system like mine quiet.

[rallynavvie]

I ditched the new install of Vista on the array and decided to keep my OS on the single Raptor and instead use the array for applications and VMs. I could have run the VMs, apps, and OS all on this array but with the amount of VMs I've been using on this machine (generally 3-4 are running at any given time) I thought it best to isolate the array. The memory on the controller combined with the drive buffers have produced a wonderful project drive for multiple VMs. The other advantage to this is I can send the drives into low-power mode when I'm away from home by putting the VMs to sleep, something I might not be able to do with an active host OS on the array.