Re: OT: Torn between SCSI and SATA for RAID
I'd rather run 5 SATA cables then one SCSI cable (say 68pin) with multiple heads... The darn SCSI cables are so thick, comparatively, that running them in your case is a lot harder :-) Well everyone's mileage may vary. Parallel cables only work nicely when you have a stack of drives all close lined up together. I personally yearn for a simple 40gbps daisychainable serial bus. I hoped firewire would have been it but we seem to be stuck at 800mpbs. The other cabling option I forgot about is USB2 or Firewire. There are a number of very low cost external cases that pre-package USB/Firewire SATA converters. You basically fill a hard disk case with SATA or ATA drives and connect your computer to the case via a single firewire or USB cable. I have not seen one of these that's hot swap yet but I did see a few of these recently in Tokyo Akihabara district for ~$100 so I assume they are available all over. The box's I have seen are 4 drive systems. Just fill them with your favorite commodity hard disk I guess. At ~50MB/s the interface is plenty fast and greatly simplifies the cable issue inside the PC. IJ ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED]
Re: OT: Torn between SCSI and SATA for RAID
On 5/10/06, [EMAIL PROTECTED] [EMAIL PROTECTED] wrote: Hi, I've been spending the last couple of days extensively looking at various options for RAID and getting some storage system in place. Performance is not really a BIG issue, but I also don't want to have things hecticly slow either. This will be a NAS type of implementation so speed would be bound by relatively speaking slow network connections in any case... Now first things first as well, I did look at Fiber Channels too - and the tecnology is just to expensive and complex for a home type implementation that I want this for. Ideally, I'd like to start at 2TB of storage (yes, those movies must go somewhere!), but I'd like to be able to grow this as times go by... I also definately want redundancy on the data, as I just lost 80GB of precious data when ironically, a 160GB SATA Seagate went out under me. Now SCSI I know, is more expensive than SATA. Whether it provides beter performance than SATA I'm still uncertain off, but gut would tell me that due to the cost factor, SCSI *should* run away as far as speed is concerned. But also as I said previously, speed and performance is not a priority for my implementation and therefore it has very little weight. This makes me look at SATA then therefore. My problem with SATA, is the whole 1 Port, 1 Drive scenario. I've looked at the Adaptec 16 Port SATA Controller. The reviews I managed to get on that card on the Internet, paints a very grim picture. Buggered Firmware, the controller destroys drives, and general sluggish performance. Is anyone using this card that can perhaps give me a better picture? You want the Areca ARC-1160-ML (ML for Multi-Lane) card: http://www.areca.com.tw/products/html/pcix-sata.htm http://www.rackmountpro.com/productpage.php?prodid=2350 http://www.freebsd.org/cgi/man.cgi?query=arcmsrapropos=0sektion=0manpath=FreeBSD+6.1-RELEASEformat=html -- BSD Podcasts @: http://bsdtalk.blogspot.com/ http://freebsdforall.blogspot.com/ ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED]
Re: OT: Torn between SCSI and SATA for RAID
Hi Chris, I have many of the same questions. SATA is plenty fast for home systems and modern drives are smoking stuff that was enterprise class just a few years ago. 'twas ever thus. Cables are a nightmare IMHO. This was by far the reason I've been a big fan of SCSI for a long time. You can make a pretty effective and tidy Raid system by custom making a short length daisy chain scsi cable. I have not explored this recently but used to do this ~5+ years ago for non-raid applications. We used to run into device compatibility problems on the SCSI bus though so same drive mfg might be a good idea. Perhaps things have improved. You can buy old 80 pin 16 bit SCSI controllers quite reasonably on EBay. Even though the bus speeds might be 40 or 80 MB/sec (that's bytes) this still exceeds what I get on single disk SATA benchmarks. My impression is that modern drives are backward compatible with older SCSI but I've not tested this extensively, just a couple of anecdotes. You can do quite well in the used Enterprise market. You might have a look at pricewatch.com for some low cost SCSI disks. My experience has been that S/P-ATA drives seem to be easily available in large sizes, 300 GB whereas SCSI seems to be available in volume only for smaller drives ~100-200GB. Above is mostly supposition. I have been experimenting with SATA to see what's possible. There are gizmo's, Backplanes, out there that make the cabling issue easier: I have one of these: http://www.mwave.com/mwave/viewspec.hmx?scriteria=BA20689 And I'm considering one of these: http://www.mwave.com/mwave/viewspec.hmx?scriteria=BA20690 Similar devices are available for SCSI and PATA drives they are a little difficult to find. You can google for backplane, 3X5 and 2X3 that type of thing. I finally got gvinum to work for me under 6.1 i386 RELEASE for Raid 5. The volume manager concept appeals to me because you can work with smaller chunks pieces of storage than whole disks. So with the same set of physical disks you can contemplate different RAID strategies depending on how much performance you want, all at the same time. So far my benchmarks indicate that a 3 partition raid 5 vinum disk performs fine for me. Minimum write performance is around 7MB/s and Minimum read is around 14MB/s. Usually however writes came in on the low side of 15 MB/s and reads around 50 MB/s. This is all just a first attempt though without any attempt to tune the raid set. With two 5X3 backplanes and software Raid 5 you could build PDQ a 4TB system and your drives would not have to be identical. Even with a backplane device though you end up with quite a cable issue. The last option I've considered is to look at some of the SATA to SCSI backplanes. There are commercial solutions that allow you to put SATA or PATA drives up to 12 in an enclosure then connect to your host computer via SCSI. I haven't found anything cheap though. Cheap = 20% of the drive cost. Apple sells such a device as do numerous other manufacturers. Search for SATA Raid. IJ On May 11, 2006, at 7:51 PM, [EMAIL PROTECTED] wrote: My questions that I'm posting is not really related towards the performance of the system, it's more towards the capacity of the system... I guess it boils down to the physical hardware... How does everything connect, how to expand systems, and how to run arrays bigger than what one single controller can provide... -- C ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED]
Re: OT: Torn between SCSI and SATA for RAID
On May 25, 2006, at 5:30 PM, Ian Jefferson wrote: Hi Chris, I have many of the same questions. SATA is plenty fast for home systems and modern drives are smoking stuff that was enterprise class just a few years ago. 'twas ever thus. Cables are a nightmare IMHO. This was by far the reason I've been a big fan of SCSI for a long time. You can make a pretty effective and tidy Raid system by custom making a short length daisy chain scsi cable. I have not explored this recently but used to do this ~5 + years ago for non-raid applications. We used to run into device compatibility problems on the SCSI bus though so same drive mfg might be a good idea. Perhaps things have improved. I'd rather run 5 SATA cables then one SCSI cable (say 68pin) with multiple heads... The darn SCSI cables are so thick, comparatively, that running them in your case is a lot harder :-) Chad --- Chad Leigh -- Shire.Net LLC Your Web App and Email hosting provider chad at shire.net ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED]
Re: OT: Torn between SCSI and SATA for RAID
I recently read an interesting comparison on consumer and enterprise grade harddisks: http://www.seagate.com/content/docs/pdf/whitepaper/D2c_More_than_Interface_ATA_vs_SCSI_042003.pdf Maybe this helps. Kind regards Lars ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED]
Re: OT: Torn between SCSI and SATA for RAID
Quoting lars [EMAIL PROTECTED]: I recently read an interesting comparison on consumer and enterprise grade harddisks: http://www.seagate.com/content/docs/pdf/whitepaper/D2c_More_than_Interface_ATA_vs_SCSI_042003.pdf This was posted yesterday in responce to my question as well. That document deals mainly with the performance and reliability of the different types of hard drives (i.e. SATA vs SCSI). My questions that I'm posting is not really related towards the performance of the system, it's more towards the capacity of the system... I guess it boils down to the physical hardware... How does everything connect, how to expand systems, and how to run arrays bigger than what one single controller can provide... -- C ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED]
Re: OT: Torn between SCSI and SATA for RAID
On May 11, 2006, at 4:51 AM, [EMAIL PROTECTED] wrote: Quoting lars [EMAIL PROTECTED]: I recently read an interesting comparison on consumer and enterprise grade harddisks: http://www.seagate.com/content/docs/pdf/whitepaper/ D2c_More_than_Interface_ATA_vs_SCSI_042003.pdf This was posted yesterday in responce to my question as well. That document deals mainly with the performance and reliability of the different types of hard drives (i.e. SATA vs SCSI). My questions that I'm posting is not really related towards the performance of the system, it's more towards the capacity of the system... I guess it boils down to the physical hardware... How does everything connect, how to expand systems, and how to run arrays bigger than what one single controller can provide... Look at the Areca SATA controllers. An 8 port RAID 6 SATA controller using 8 drives, 1 a hot spare, gives you about 5 drives worth of RAID 6 (5 + 2 parity = 7 drives, can suffer up to 2 simultaneous drive failures) and the Areca seem to be well regarded. I have an 8 port and a 12 port one but not in service yet. Areca has FBSD drivers. 5 drives * 500GB is a about 2.125 real TB (given that 500GB drive is not really 500 real GB) (calculation made with simple ratios and could be way off). The 12 port Areca card with 1 hot spare and RAID 6 would give you 9 * 500GB = about 3.825 real TB To get the size of array you want you need to go SATA as the SCSI drives aren't really big enough to get that big without getting into major major money. Use good, 24/7 rated SATA drives, not cheap maxtor or WD (think seagate or hitachi probably). Buy an extra drive to have or lose some capability and set up 2 hot spares. I am considering a machine with 2 12 port Areca cards set up with 2 RAID 6 arrays mirrored using ZFS under Solaris 10 as an nfs storage server... Chad --- Chad Leigh -- Shire.Net LLC Your Web App and Email hosting provider chad at shire.net ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED]
OT: Torn between SCSI and SATA for RAID
Hi, I've been spending the last couple of days extensively looking at various options for RAID and getting some storage system in place. Performance is not really a BIG issue, but I also don't want to have things hecticly slow either. This will be a NAS type of implementation so speed would be bound by relatively speaking slow network connections in any case... Now first things first as well, I did look at Fiber Channels too - and the tecnology is just to expensive and complex for a home type implementation that I want this for. Ideally, I'd like to start at 2TB of storage (yes, those movies must go somewhere!), but I'd like to be able to grow this as times go by... I also definately want redundancy on the data, as I just lost 80GB of precious data when ironically, a 160GB SATA Seagate went out under me. Now SCSI I know, is more expensive than SATA. Whether it provides beter performance than SATA I'm still uncertain off, but gut would tell me that due to the cost factor, SCSI *should* run away as far as speed is concerned. But also as I said previously, speed and performance is not a priority for my implementation and therefore it has very little weight. This makes me look at SATA then therefore. My problem with SATA, is the whole 1 Port, 1 Drive scenario. I've looked at the Adaptec 16 Port SATA Controller. The reviews I managed to get on that card on the Internet, paints a very grim picture. Buggered Firmware, the controller destroys drives, and general sluggish performance. Is anyone using this card that can perhaps give me a better picture? Given than the 16 Port (for now) is out of the question, I have a 8 Port, 4 Port and 2 Port (which isn't really worth looking at even) available to me. Now, even with a 8 Port card... Let's look at what I can achieve: Ports 1+2: 750GB Seagates (Biggest available), 1.5TB - I'm short on my 2TB Initial Ports 3+4: Mirror of 1+2 Already, I am coming short of what I want to achieve, and I also have no expansion available to me for upgrades... With the 16 Port cards, what I want to achieve becomes quite possible, up to easy about 6TB of data - but I risk loosing drives *IF* what I read about the card is true. Also a gamble, considering the relatively high price of large SATA drives. Another thing that I read that I'm not completely sure about. Some of the Adaptec SCSI Cards advertises a max of 30 devices - some even more. Excuse the ignorance, but does the SCSI Bus not allow for a max of 8 devices? Do these cards then feature multiple buses to connect the cables to? If so, SATA will obviously not be able to provide something like this. Now comes my question... Uhm.. Can SATA RAID Controllers be 'linked'. Say, I but 4 x 8-Port Adaptec SATA RAID Controllers... 2 x 8 Port Cards = 16 Ports for 1 RAID 5 Array (@ 750GB Drives, 12TB Max). The other 2 cards, to mirror. I know that I can use one Controller to mirror another, but can I extend a array across multiple controllers... And then naturally, just HOW much slower does the array function? I've seen some comments and posts (esp. on slashdot) made where people go about running massive arrays successfully on SATA. Given the limits on the Ports at the controller, just how is this achieved? Sorry that this is so OT, but I hope I'd get some good answers. This is definately not something that's been discussed allot before considering the amount of info I got after spending a number of days on google... -- Chris. ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED]
Re: OT: Torn between SCSI and SATA for RAID
I've found that scsi isn't exceptionally faster given similar RPMs, or even slightly higher RPM (ex. a 10K RPM SCSI vs. 10K RPM SATA drive would have simlar performance). However, SCSI tends to high tighter standards, and you get the following advantages, which in some cases are worth the money, and in some cases arent: (1) More reliable/accurate reads/writes (2) Longer expected lifespan My advice for reliability is a RAID-1 setup with the most cost-effective disks you can find, then use the OS to do a drive spanning so you can put them in the same mount point (when it runs to the end of a disk, it starts on the next). I'm not sure if the drive spanning is possible though - I've not looked into it, though given that Windows can do it, I don't see why FreeBSD would have trouble. If that is still too expensive, you could try RAID-5, but the problem with that is, adding new disks wouldn't be quite as easy, you may not be able to use the RAID set until you get the replacement disk, and it's not quite as fast (I could be wrong on this part) as RAID1 in the case of writes. with a 8 Port card... Let's look at what I can achieve: Ports 1+2: 750GB Seagates (Biggest available), 1.5TB - I'm short on my 2TB Initial Ports 3+4: Mirror of 1+2 Maybe I'm missing something, where ports 4-8 (actually, 0 + 4-7)? With 8 500GB drives, and RAID1, you should be able to get 2TB out of that (and more cost effective than 750GB drives) Have you considered using two controller cards? nother thing that I read that I'm not completely sure about. Some of the Adaptec SCSI Cards advertises a max of 30 devices - some even more. Excuse the ignorance, but does the SCSI Bus not allow for a max of 8 devices? Do these cards then feature multiple buses to connect the cables to? If so, SATA will obviously not be able to provide something like this. 8 devices, 1 is the controller, I think some newer busses hold 16 devices, is is the controlelr, (so 7 or 15 drives). Now, a card may have multiple busses. I have an A-Ha 39160 in my machine, and if I remember correctly it has 2 busses on it (or is it three?), I don't use it to nearly it's capacity, I just got it for the price of a 19160, and I couldn't turn down that option. Now comes my question... Uhm.. Can SATA RAID Controllers be 'linked'. Say, I but 4 x 8-Port Adaptec SATA RAID Controllers... 2 x 8 Port Cards = 16 Ports for 1 RAID 5 Array (@ 750GB Drives, 12TB Max). The other 2 cards, to mirror. I know that I can use one Controller to mirror another, but can I extend a array across multiple controllers... And then naturally, just HOW much slower does the array function? The array will be using system cpu/memory, so quite a bit, and it'll cause a hit on system perofrmance, however, the trick here is you can do what I mentioned above with some trickery (I think), and just have the OS link the two file systems, it's not any RAID form, and shouldn't cost much performance. ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED]
Re: OT: Torn between SCSI and SATA for RAID
On Wed, 10 May 2006 12:00:00 +0200 [EMAIL PROTECTED] wrote: Hi, I've been spending the last couple of days extensively looking at various options for RAID and getting some storage system in place. Performance is not really a BIG issue, but I also don't want to have things hecticly slow either. This will be a NAS type of implementation so speed would be bound by relatively speaking slow network connections in any case... http://www.seagate.com/content/docs/pdf/whitepaper/D2c_More_than_Interface_ATA_vs_SCSI_042003.pdf -- Bill Moran Collaborative Fusion Inc. ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED]
Re: OT: Torn between SCSI and SATA for RAID
Another thing that I read that I'm not completely sure about. Some of the Adaptec SCSI Cards advertises a max of 30 devices - some even more. Excuse the ignorance, but does the SCSI Bus not allow for a max of 8 devices? Do these cards then feature multiple buses to connect the cables to? If so, SATA will obviously not be able to provide something like this. I am not that familiar with SCSI protocols, but I imagine the Ultra-Wide SCSI bus can probably address 32 devices ( 31 drives + the controller ). Now comes my question... Uhm.. Can SATA RAID Controllers be 'linked'. Say, I but 4 x 8-Port Adaptec SATA RAID Controllers... 2 x 8 Port Cards = 16 Ports for 1 RAID 5 Array (@ 750GB Drives, 12TB Max). The other 2 cards, to mirror. I know that I can use one Controller to mirror another, but can I extend a array across multiple controllers... And then naturally, just HOW much slower does the array function? I imagine you would probably have to use software raid at that point. And even if you would use two controllers togeather (SLI for RAID?) you would be limited by the PCI bus. I've seen some comments and posts (esp. on slashdot) made where people go about running massive arrays successfully on SATA. Given the limits on the Ports at the controller, just how is this achieved? Probably with softawre RAID. With software RAID you can even mix drive types, like SATA, PATA, SCSI, USB, etc. But it's much slower. Sorry that this is so OT, but I hope I'd get some good answers. This is definately not something that's been discussed allot before considering the amount of info I got after spending a number of days on google... -- Chris. ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED] -- -- Perfection is just a word I use occasionally with mustard. --Atom Powers-- ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED]
Re: OT: Torn between SCSI and SATA for RAID
Atom Powers wrote: Another thing that I read that I'm not completely sure about. Some of the Adaptec SCSI Cards advertises a max of 30 devices - some even more. Excuse the ignorance, but does the SCSI Bus not allow for a max of 8 devices? Do these cards then feature multiple buses to connect the cables to? I am not that familiar with SCSI protocols, but I imagine the Ultra-Wide SCSI bus can probably address 32 devices ( 31 drives + the controller ). Old 8-bit SCSI allow for 8 devices. For HD today you'll want Wide (16-bit) SCSI, which allows for 16 devices (15 drives + controller). There is no 32-bit SCSI, AFAIK. The Adaptec cards you mention do have two busses (basically they are two controllers on one chip and are as such seen by the OS). Can SATA RAID Controllers be 'linked'. ... can I extend a array across multiple controllers... I imagine you would probably have to use software raid at that point. Yes and true. And even if you would use two controllers togeather (SLI for RAID?) you would be limited by the PCI bus. You might want a motherboard with multiple PCI buses and carefully choose the RAID scheme vs. HD distribution. If you need so many drives, however, you might well be better off with an hardware solution. Probably with softawre RAID. With software RAID you can even mix drive types, like SATA, PATA, SCSI, USB, etc. But it's much slower. I wouldn't want to do that... I've always heard you should get identical drives to build an array. Of course you might have different arrays on the same machine... bye av. ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED]
