SATA controller hot swap?

> Sometimes I just assume that others will assume and I guess that's far too
> many assumptions.
>
> I'm well aware of the need for RAID and the proper hardware to accomplish
a
> hot-swap. Those things have explicit documentation and guidelines readily
> available. What isn't well documented or known is whether all SATA
> controllers are by nature able to be used in a hot-swap situation assuming
> all else is capable (the drive, physical bay, os, etc...) I'm trying to
> decide on a controller and cannot as of yet come to a conclusive choice.
>
> My setup includes a server rack-mount case with 8 front 5 1/4 bays filled
> with drive swap trays.

Trays? You need drive enclosures (cages) and drive carriers (trays).
What brand/model of cages/trays did you get?

> The setup will include 6 drives for now, 2 being
> part of one set and 4 being part of another set. The set of 2 will be a
> RAID 1 mirror set, and the set of 4 will be a 0+1 striped set of 2
mirrored
> to the other 2. The idea is for the mirror drives to be swaped on a
> schedule to have an off-site duplicate of our data.

Interesting concept. Do you know that upon insert of replacement drives,
array rebuild process starts?
And in most cases it runs for quite a time, degradating system performance.
How much? That depends on RAID controller and level of system activity. If a
wrong second drive is pulled, or is pulled to early, filesystem might get
damaged.

> The 2 drive set would
> be swapped every day and take place of 8 of our current tape drive based
> daily backups. The 4 drive set would be a place to store whole machine
> images, and an archive history of files so we could recover last week's
> version of your documents. This is intended to be a NAS device that will
> replace all of our tape backups and expand our backup/restore
capabilities.

Of course you will need to rewrite tape backup procedures to adopt NAS
approach.

> I'll be using SATA 150 drives at 400G each for now giving us a daily 400G
> store and a long term 800G store. All in all I'll have 2.4 TB online with
> 1.2 TB effective (since it's all mirrored). And of course with the room
to
> add two more drives to the long term storage to bring that up to 1.6
> effective. Did I mention that the price tag is currently under $3,000.
The
> same setup from Dell is around $12,000. Granted, they use SCSI 320 drives
> at over $1,000 each - but my concern is total space, not per second speed.
> Backups have 8 hours at night to run over a dedicated Gigabit ethernet
> subnet, I wouldn't care if it took only 1 of those hours instead of 3.
> That's not worth $9,000 to me.
>
> Basically, the bottom line is that unless I can confirm from the
> manufacturers mouth that their card is capable, I'm on my own crossing my
> fingers, although chances are good that most anything I get will work. I
> would have thought that it would be more concrete than that, but in
reality
> it doesn't seem to be.
>
> Case in point: In my personal computer I'm running an nForce2 board with
2
> on-board SATA ports. The online manual, the website, nor the reseller had
> any note of it being RAID capable. I found a user online with the same
> board who said it was. I took a chance, and when it arrived the box nor
the
> manual made any mention of RAID, however upon boot, there it was. The
RAID
> controller clearly announced itself and I'm running a nice and fast
striped
> set for my system and game partitions.

Which motherboard was that?

> SATA RAID and hot-swap capabilities (as far as controllers are concerned)
> are just as inconsistent as USB used to be with their 'high speed' vs.
real
> 'USB 2.0' support. I remember reading that there was no official rule
> stating how to label 2.0 vs. 1.1 for a time and some hardware makers would
> label products 'high speed' that were not truly USB 2.0.
>
> It should be required on all SATA controllers to not just omit things like
> hot-swap or RAID, but to expressly note when either is not applicable.
Not
> showing RAID or hot-swap in the description is not as intuitive as saying
> RAID: NO / Hot-Swap: NO. That responsibility probably lies with the
> hardware reseller and I've not found one yet that does it that way.
>
> In the end, I think I've gotten the help I need from the community and I
> thank you all. I have to rely on confirmation from specific manufacturers
> at this point on a per-card basis until I've had enough personal
experience
> to reliably assume support or non-support.

Good approach. Run your NAS paralled to tape based backup procedures for a
while.

Don't forget to check hardware claimed reliability numbers. Last time I have
checked, RAID SATA cotrollers had relatively low numbers.

>
> Thanks again to everyone.
>
> --
> Shawn Wilson
>

"Peter" <peterfoxghost RemoveThis @yahoo.ca> wrote
>>
>> My setup includes a server rack-mount case with 8 front 5 1/4 bays filled
>> with drive swap trays.
>
> Trays? You need drive enclosures (cages) and drive carriers (trays).
> What brand/model of cages/trays did you get?

Yes, they are drive cages and trays together, just figured the word tray was
enough. Good attention to detail though.

Not a 'name' brand. I'm finding them in several places (I'm spec'ing out
the system, haven't purchased anything yet)

>> The setup will include 6 drives for now, 2 being
>> part of one set and 4 being part of another set. The set of 2 will be a
>> RAID 1 mirror set, and the set of 4 will be a 0+1 striped set of 2
> mirrored
>> to the other 2. The idea is for the mirror drives to be swaped on a
>> schedule to have an off-site duplicate of our data.
>
> Interesting concept. Do you know that upon insert of replacement drives,
> array rebuild process starts?
> And in most cases it runs for quite a time, degradating system
> performance.
> How much? That depends on RAID controller and level of system activity. If
> a
> wrong second drive is pulled, or is pulled to early, filesystem might get
> damaged.

I actually may modify my concept to allow for two 4port controllers instead
of one 8 based on cost and no 64bit PCI slots. That would mean though that
the raid cards wouldn't be handling the mirror process unless I could tie
two controllers together somehow. This is still up in the air though.

Since this is a NAS backup box with nothing else to do except keep track of
those drives, it can be as busy as it wants to be. It's only job will be to
keep that data as a backup, we won't be accessing it live unless we'd need
to restore (and that wouldn't be anytime around the time we're swaping
drives anyway)

Yes, the rebuild is exactly what I need to happen, so when I remove a mirror
drive and put in another, the one I just put in gets sync'd to what's on the
one that stayed in. This all should happen automatically, right? Even if I
had to use some software to tell it to start, that'd be ok, but just one
more step to remember.

For the stripe set, I would imagine I would need to remove all 3 mirrors,
then put in the swaps in order for it to work without issue.

>> The 2 drive set would
>> be swapped every day and take place of 8 of our current tape drive based
>> daily backups. The 4 drive set would be a place to store whole machine
>> images, and an archive history of files so we could recover last week's
>> version of your documents. This is intended to be a NAS device that will
>> replace all of our tape backups and expand our backup/restore
> capabilities.
>
> Of course you will need to rewrite tape backup procedures to adopt NAS
> approach.

Oh yes, and we can delete whole sections about making sure the tapes aren't
too old... where fresh tapes are kept... waiting on the tape to eject...
what to do if it doesn't eject... making sure there aren't any errors
reported... blah, blah, blah... man I hate dealing with tapes... This
instruction sheet will go from 50 steps to 2 real quick. (exhagerating, but
you get the idea)

Not to mention the added bonus of the fact that the entire NAS box costs
less than 2 of our tape drives. This box will pay for itself in 2 years
assuming a 50% failure rate on the new hard drives or controllers. Less
than 1 year if things last as long as I'm used to with my own experience
with SATA drives. (the failure rate is overkill I think even for disaster
planning, but I wanted to cover worst case)

>> Case in point: In my personal computer I'm running an nForce2 board with
> 2
>> on-board SATA ports. The online manual, the website, nor the reseller
>> had
>> any note of it being RAID capable. I found a user online with the same
>> board who said it was. I took a chance, and when it arrived the box nor
> the
>> manual made any mention of RAID, however upon boot, there it was. The
> RAID
>> controller clearly announced itself and I'm running a nice and fast
> striped
>> set for my system and game partitions.
>
> Which motherboard was that?

My personal motherboard is currently an MSI nForce2 board... although I'm at
work and can't recall the model number. It's DDR400, Athlon XP, 2 SATA
ports, AGP 8x, dual NICs (one gigabit). Google searches are making me think
it's a KT4 Ultra, however today I'm getting much more information and it's
quite prevelant that the onboard SATA supports RAID. I don't remember mine
being 'bluetooth ready' but it must be since this looks like my board.

I'm trying to decide on an upgrade path, but I'm holding off just a bit
because I can't decide on PCIe vs AGP for my next video card. My question
there isn't about performance ceiling so you don't need to tell me about the
glorious PCIe. I've been keeping up on it and realize the potential for
PCIe, but in my price range I can go either way and have the same
performance. My last thought was looking at an X800, but that's on a back
burner and off topic.


--
Shawn Wilson