Because such numbers can severely mislead you, and end up making you wonder:
"Why is this pile of junk dragging serious butt, when tests show I'm getting over 1GB/s?!?!?" 😉 😛
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Boot off RAID 0 in Mac Pro
- Thread starter HyperX13
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"Why is this pile of junk dragging serious butt, when tests show I'm getting over 1GB/s?!?!?" 😉 😛
AJA system test
I did a aja system test : disabled system cache
video frame size PAL DV25 file size 4.0 GB
Write 198.3
Read 234.9
I don't understand how the results with a raid 5 and 4 disks of 300 gig, can be so much better then mine wich are also 4 disks of 300gig only they are even faster with 15.000 rpm scsi connections and raid 0 .
Am i setting the raid up with the wrong blocksizes or something like that, or is there something else going on?
I did a aja system test : disabled system cache
video frame size PAL DV25 file size 4.0 GB
Write 198.3
Read 234.9
I don't understand how the results with a raid 5 and 4 disks of 300 gig, can be so much better then mine wich are also 4 disks of 300gig only they are even faster with 15.000 rpm scsi connections and raid 0 .
Am i setting the raid up with the wrong blocksizes or something like that, or is there something else going on?
You can play around with the stripe size to see what best fits your usage (not just benchmarks, use a new stripe size with the applications you will use, the same way you intend to).
As per the type 5 array, it's a parity based array to give some redundancy, and alphaod's setup has 2x as many members as your set. So the parallelism aids in the speed (load shared across more drives = faster throughput for reads). RAID 5 has limitations (notable in the case of the write hole), so you can do some research on this one if you're curious. 😉
DoFoT9
macrumors P6
As soon as i find the time i'm gonna make a external hd my system disk and then see what speeds i can get if the system is not running on the same raid 0 partition, , lets see what happens then.
DoFoT9
macrumors P6
that will be interesting but why does the boot drive have to be external? or do you mean external to the RAID? lol
Both actually, i want to know why my raid 0 numbers are so low with 4 sas 15.000 rpm drives, around 200MB/s , if i just hookup a external e-sata with a regular 7200 rpm drive i get close to that already so thats not right.
The only thing i can think of is that the speed goes down, because the system is on that raid0 array, so if i just boot from an external drive ( e-sata) then i should get the best speeds of my 4 internal sas drives in raid 0.
If this works well i'll be getting a external raid0 enclosure with e-sata connectivity to keep my system fast two and use the internal drives just foor the media .
That is awfully slow. 🙁
Which SAS drives are you using?
I'm thinking you should be in the neighborhood of ~600MB/s (assuming they're able to achieve ~150MB/s sustained reads).
The processors on Apple's RAID cards aren't the fastest, and will throttle you. But it usually occurs in parity based arrays, as the processor is getting a good workout. IIRC, the processor in your card is a 333MHz PPC, with the newer version stepped up to a 500MHz unit.
Also, which slot is the card in (just curious)?
This shouldn't be the case though. SAS is faster at random access (OS usage) than SATA in either single or RAID usage.
OS X also stays on the faster tracks, as it's not "sprawled out over the entire drive" as it is with Windows (OS files it stuffs on the inner most tracks of a drive/partition).
If it were Windows, you would see a decrease in throughput, but it still wouldn't be that bad. I mitigate it by creating a short stroke partition for the Windows installation. But this shouldn't be the case.
Sorry for my late reply, i just now found out you had replyed to me.
The card is in slot 4, and the drives are seagate cheetah 15.000rpm sas drives of 300 gig.
Its a mistery to me how come that this set up is so slow, and another problem i have is that, if i start up the mac i will have to do that a couple of times before it will find the startup drive ( being the raid0) , thats not normal either i think, but no luck in finding out what the problem is there either.
The card is in slot 4, and the drives are seagate cheetah 15.000rpm sas drives of 300 gig.
Its a mistery to me how come that this set up is so slow, and another problem i have is that, if i start up the mac i will have to do that a couple of times before it will find the startup drive ( being the raid0) , thats not normal either i think, but no luck in finding out what the problem is there either.
you must be able to do this. I am looking to do this fairly soon. I want to replace my 4x1TB drives that came with the MacPro with 4x2TB drives. From memory, the OS was installed on one of the drives and then I made them all Raid 0 afterwards. I could be wrong though... I've spoken to at least 3 Apple care specialists who all say it can be done no problems. I will still be sitting down with them on the phone for as long as it takes to make sure it is all going ok. I also have the apple raid card and back up everything to a drobopro with time machine. My plan is to take out the existing drives, put in the new ones, install SL, raid 0 them and then from drobo, replace the content form time machine. Sounds easy enough, but I know something is going to pop up!
nanofrog - I wish I'd done more research on the apple raid card before buying, I just assumed the apple stuff was the 'ducks nuts' so to speak... 🙁
You mentioned that it's slow; is that slower than other raid cards / software raid, or slow enough that I shouldn't bother 'raid zeroing' my computer?
It's possible the drive's firmware isn't the best for that card. Usually you check the Hardware Compatibility List (name may vary), to see what drives were tested with the card and passed. It also includes the drive's firmware revision (it really makes a difference). Unfortunately, I've never seen one from Apple. You'd have to call, and see what information you can get out of them.
Overall, I'd recommend dumping the Apple card, and going with another make. They're faster, have better features, work with more than one OS, and cheaper in some cases (depends on the exact model). I presume you wish to boot from the array, so get one that has EFI based firmware. Areca or ATTO Technology would be companies to look at. The simplest would be the ARC-1212 (4 port SAS card, and it will boot EFI for you once flashed, as the default is BIOS).
If you need to grow, I'd also recommend getting a card with more than 4 ports, as it's easier to add drives for online expansion than swapping them out. BTW, you can run internal ports to external enclosures with the right cable. You must watch the distance of cables though, especially with SATA drives, as it's much shorter than the limit for SAS.
Yes you can boot off of an array, whether software based or hardware based (if it has EFI boot capability).
Unfortunately, Apple's card is half-baked at best, given it's lackluster performance,....
They're just slow. Slower than any decent RAID card. It's not likely to be much off of a software based array for a stripe set (cache should help a little). It's real benefit is the fact it has the ability to run a type 5 array. The NVRAM is there to eliminate the write hole issue, but since the battery on it isn't reliable, it's not even good for that.
Seriously, get rid of it. If you only want a stripe set with SATA drives, run them off the logic board. This will allow you to get a better card if you need it (either more drives than are possible in the MP, SAS disks, or parity based arrays).
Yeah i get the feeling selling it would be the best to do, because in this way might aswell make a software based striped raid with 4 sata drives, that is probably just as fast, i only bought it for speed and not for safety, i have timemachine for that.
I will have to find someone who is intrestted in it do, that will be the difficult part.
BTW if i would just set all the sas drives up as jbod and then make a software stripe, would i be working around the card and get the speed of the sas drives any way, or will the card always be the bottle neck if it is in the machine .
I will have to find someone who is intrestted in it do, that will be the difficult part.
BTW if i would just set all the sas drives up as jbod and then make a software stripe, would i be working around the card and get the speed of the sas drives any way, or will the card always be the bottle neck if it is in the machine .
eBay.
You can't use the SAS disks on the logic board, so you will need a card for that. Sorry about any confusion here. 😱
Assuming you don't need additional ports (4), then take a serious look at the ARC-1212 (linked above). 4 port, SAS card, and it can boot OS X once it's been flashed with the EFI firmware.
I've used them professionally and for my personal system as well (different models, but the one linked will work quite well, as it's very similar to the 1680 series, just SAS expander support was eliminated).
Assuming you use this card (or another), you can do what you want with it in terms of array level (provided you've enough drives for the levels it supports). As you've 4x SAS disks, you can even go with a RAID 5 if you choose.
Just make sure you've a UPS, and the battery option for the card is a good idea too.
I think you miss understood my question, if i leave the apple card in there ( so that i have support for the sas drives) and dont configure a raid 0 with the card but just set all the drives as JBOD, and then make a software raid in osx would i then be able to get the speed of the sas drives without the slowdown of the raid card.
In that case i won't need another card to get the speeds, again i only want speed from the drives no safety.
It should be possible, but given the card's performance otherwise, I'm not sure (JBOD does require a little bit of work by the card as well). I'm thinking it would still work slowly, as I suspect the drive firmware revision.
That means you'd need to flash the drive firmware with one that works better (presumably newer revision), or get another SAS card of some sort.
Ok bassicly ill have to give it a try then and see what that does ;-).
Ty for your help and suggestions
Ty for your help and suggestions
For drive firmware, you may end up having to contact both Apple and Seagate, but start with Apple, as they made the card, and hopefully have information regarding the firmware revision of the drives you have that are verified as working.
Let's hope they actually tested this, and not sent a product out without any verification as per drives. 😉
I looked on the web , and apple say only there apple branded drives are supported, i also just saw that i have 1 drive that is diffrent from the other 3, probably newer,3 drives are : ST3300555SS , and 1 is : ST3300656SS , i cant see what drive firmware is on them in the raid software ,so i dont know.
ST3300555SS = Cheetah T10
ST3300656SS = Cheetah 15K.6
In a mixed drive environement, the slowest drive will affect your speed, and given the different model, the older one may not be that compatible. Try removing it from the set, and redeploy the stripe on 3 drives (all 15K.6's). I know it's work, as you have to backup everything first, and reconstruct the array, but that drive is the possible culprit.
And IIRC, the 15K.6's are what Apple uses as their OEM supplier for their SAS drives.
I'm used to the utility that you use to control the card's settings will have that information available. But I've not used the Apple card myself, so am unfamiliar as to tell you exactly where to look.
I have only 1 15K6 drive unfortunatly not 3, so all i can see that i can do is stripe the 3 older ones and use the newer 15K6 as a system drive then.
Oops. 😱 Got the quantities backwards.
I'm not sure if the older drives are truly compatible with the card, but you need to find out, so testing is the only way to find out. If you have issues, you're going to have to contact Seagate about it, and see if they've different firmware you can use with it. BTW, those drives were released in 2006, and are older than the system and card.
As it happens, the ST3300555SS isn't listed on Areca's HDD page either. But the 15K.6 version is with either card as I understand it (going by Apple using the Seagate 15K.6's as the OEM drives).
Yeah i was afraid of that, i bought those second hand the older ones, at the time i did not know it was so important, aslong as it were 15.000rpm SAS drives. did not think about compatability at all, it is my first raid card so i was new to it, shame on me.
Live and learn. 😱 😀 😛
Seriously, any time you end up trying to mix old and new gear in RAID systems, this tends to happen.
Sometimes you get really lucky, and it all works. Others, you can get it to work after chasing down firmware (card or drives). But there's instances it just won't work, no matter what you try. In these situations, you have to dump something, and start over.
In the case of old drives with a new card, it's best to replace the drives. But in your situation, I'm thinking both may need changing.
If you can't get it to work with those old drives, dump the card first. Then try the Areca I linked (or a different SAS model, as I've only linked the closest model in terms of specs to the Apple card). There's a good chance it would work with the existing drives, as they can't test every drive model out there. Too expensive in terms of both drives lying around and time. Testing has to be thorough, so it's time consuming.
If they don't work with the Areca, then get new drives. It sucks, but it could come down to this. 🙁 I really hope not though. 😉
I get what your saying, but i already spent so much money on this, i won't put anymore in it, the start up problems aside, the system works as it is now, only the speed is not realy high, if i can't get it any faster then this i will sell both the drives and the card and stick with software raid0 and maybe raptor drives for speed, no more raid cards with sas drives for me if this is not woking out ;-).
Understandable. If you don't actually need SAS and can't get what you have to work, then dump it.
I'd even recommend skipping the Velociraptor, as there's newer 7200 rpm drives that can exceed it in terms of sequential throughputs. It still has an edge in random access, but it's pricey. You can stripe cheaper drives and get the random access down anyway (in an ideal case, say half that of the normal access times).
If you really want a fast boot, then you'd want to put the OS and applications on an SSD. By at least splitting off the data, you can cut down on the capacity requirement for the SSD, so an 80GB unit is likely to suffice. The Intel 80GB Gen 2's were up on newegg today at $300USD for the retail version. Same $$$ basically as the Velociraptor, so it's up to you.