ATTO R680 or Areca 1880x

[nanofrog]

I gave the SW vendor a quick call. The app is truly multi threaded. Multi core CPU, amount of RAM and random read IOPS increase productivity - that's what the guy have said.
I think I'll go with two arrays (will still give some more thought to it):
Two MLC based SATAIII SSDs in RAID0 (for this particular app, highest possible performance, no need for parity)
Remaining six disks (have to think which) in RAID5 (?) for video editing (Premiere / AE).

I believe mixing disks like this in the enclosure wouldn't be a problem.

For the particular software (financial suite), it looks like SAS or SSD is the way to go then (did they happen to give you a number for IOPS?).

The other two factors, is capacity and budget to get any further on the specifics.

Also, as per the library, if it doesn't change often (application isn't writing to that particular set), then you could get away with a stripe set if you can afford the time needed to fix it (remember, you'd have to do this manually with RAID 0 = replace disk, then restore the data from a backup). If you can't put in the time, or the application will frequently update the set, then a redundant array is called for (if it's MLC based SSD's, then stick to 1 or 10, for a redundant level). You'll have more options with SAS, as they can take parity based arrays (straight forward or nested variants = 50/60/51/61).

As per the video editing, mechanical SATA is the way to go (assuming this system isn't going to be used as a SAN). RAID 5 gives a nice balance of redundancy, price, and performance, but should only be undertaken if you or someone else you trust will have daily access to the system just in case there's a failure (that way it can be dealt with quickly, particularly if you don't run a Hot Spare).

If it's a remote system, or a qualified person doesn't have access to it on a high enough frequency (i.e. may only have a tech show up when it breaks, and they have to drive in - not something that can be done via a remote access client), then RAID 6 + Hot Spare would be in order.

 

[Honbe]

He didn't give any number for IOPS.
I think I can go with no parity RAID0 for the financial app. About 400 GB would be more than enough. So that most probably SSDs. Regular backup.
The system is DAS with daily access to it, therefore for video editing I think I can go with RAID5. Does it make sense to use SATA III over SATA II here? Also, would those 10k Velociraptors make any difference?
Would I be able to mix all above in one external enclosure?

BTW, I really appreciate your efforts. If you happen to be in Prague sometime just let me know, we have some really good beers here

 

[nanofrog]

He didn't give any number for IOPS.
I think I can go with no parity RAID0 for the financial app. About 400 GB would be more than enough. So that most probably SSDs. Regular backup.
The system is DAS with daily access to it, therefore for video editing I think I can go with RAID5. Does it make sense to use SATA III over SATA II here? Also, would those 10k Velociraptors make any difference?
Would I be able to mix all above in one external enclosure?

SATA II for mechanical disks will be fine (make sure you get enterprise models listed on the HDD Compatibility List for whatever card you decide).

As per all of them fitting the enclosure, so long as you have enough bays in it, and the cables are connected, Yes.

 

[Honbe]

I'd like to get rid of my current eSATA RR card and SATA enclosure with 4 disks (used for backup). That makes my CURRENT disks count of 12. With some space to grow, I can maybe get a RAID card with less ports along with SAS expander enclosure (instead of planned SansDigital TR8X).
I understand SAS expander enclosure can be connected by just one port. Is there any disadvantage (performance) to do this?

 

[nanofrog]

I'd like to get rid of my current eSATA RR card and SATA enclosure with 4 disks (used for backup). That makes my CURRENT disks count of 12. With some space to grow, I can maybe get a RAID card with less ports along with SAS expander enclosure (instead of planned SansDigital TR8X).
I understand SAS expander enclosure can be connected by just one port. Is there any disadvantage (performance) to do this?

eSATA + Port Multiplier enclosure = cheapest way to backup your system.

All of the SAS RAID cards can be used with SAS Expanders. As per using a single port to the SAS enclosure, it gives you a bit less than the throughput of 4x ports (minus the latency associated with switching between disks). Though most SAS expanders do only connect via a single port, there are some that use 2x SFF-8088 connectors as inputs (higher disk count models).

So 4 * 540MB/s = 2160MB/s, but it won't be that high. Not exactly slow, and should suffice, but just so you know (will become more prominent the more disks you're using).

But the most important thing to consider by using the SAS card + SAS Expander enclosures, is cost. Not just the enclosure, but you must use enterprise grade HDD's in order to be stable (WD RE4 GP = Green Enterprise are suited to backup, but cost more than their consumer counterparts). For example, the 2TB RE4GP is $200 each, while the consumer variants @ 3TB is ~$150.

So it's something to keep in mind, particularly as budgets tend not to be unlimited.

 

[Honbe]

I am not thinking about the SAS expander just for backup. See my above posts - I would need 2 disks in RAID0 for my financial SW and another 6 disks in RAID5 for video editing. Total 8 disks for which I planned SansDigital TR8X. Now I have currently this SATA enclosure with 4 disks for backup.
So that I've thought I can consolidate everything in one enclosure (and get rid of the RR eSATA card in the process). As it is in total 12 disks, I would need 3 ports from the RAID card AND 8 bay enclosure would not be enough. Therefore MAYBE to get cheaper SAS RAID card with just one internal and one external connector, I will be able to connect this SAS expander enclosure with one cable and still have sufficient number of bays.

 

[nanofrog]

I am not thinking about the SAS expander just for backup. See my above posts - I would need 2 disks in RAID0 for my financial SW and another 6 disks in RAID5 for video editing. Total 8 disks for which I planned SansDigital TR8X. Now I have currently this SATA enclosure with 4 disks for backup.

I realized this (primary + backup pools on a single card and single external enclosure if you can find one with enough bays in a format you like - most large format SAS Expanders are rackmounts, not pedestal). You can of course, use multiple enclosures, particularly with SAS Expander boards in them.

The downside, is cost for what you're doing.

There are instances where this is necessary, such as a large-scale SAN configuration = too much capacity to realistically manage any other way, including the speed of backup operations. But what you're trying to do doesn't fall into this category.

You'd be better off to use a separate card (there are other options to the simple eSATA cards), but I'm not sure you'll even need those, as a 2x port eSATA card will be able to handle up to 10x disks (5x disks per port is the max limit of disks on eSATA PM chips).

So that I've thought I can consolidate everything in one enclosure (and get rid of the RR eSATA card in the process). As it is in total 12 disks, I would need 3 ports from the RAID card AND 8 bay enclosure would not be enough. Therefore MAYBE to get cheaper SAS RAID card with just one internal and one external connector, I will be able to connect this SAS expander enclosure with one cable and still have sufficient number of bays.

You can, but there are other alternatives that will do what you want (would be 2x enclosures, which is actually easier to distinguish between primary and backup storage pools).

More importantly, these alternatives are cheaper than SAS Expanders (can allow you to use consumer grade disks for backups). Trust me, don't underestimate the cost factor here, as multiple enterprise disks add up fast.

It's up to you, but I'm assuming you're not on an unlimited budget here. If this isn't the case (do have an unlimited budget), then let me know.... I'll help you spend it (I can even send you a bill for consulting fees).

 

[Honbe]

I wish I had an unlimited budget
Considering all your efforts and help I think the consulting fee would be justified.

The SAS expander enclosure will probably be an overkill. I will stick with my original plan, will keep the 4 backup disks in the SATA enclosure and get 8 bay SAS enclosure together with the RAID controller as planned.
Is something like this http://www.pc-pitstop.com/sas_cables_adapters/AD8788-2.asp better than the SFF 8087 to SFF 8088 cable? Will the total limit of 1m for SATA disks apply for this adapter also?

 

[nanofrog]

Considering all your efforts and help I think the consulting fee would be justified.

Thanks. I appreciate the compliment.

The SAS expander enclosure will probably be an overkill. I will stick with my original plan, will keep the 4 backup disks in the SATA enclosure and get 8 bay SAS enclosure together with the RAID controller as planned.

Best way to go IMO, as it does help out with budgets (cheapest way to go about backing up a RAID it in my experience).

Is something like this http://www.pc-pitstop.com/sas_cables_adapters/AD8788-2.asp better than the SFF 8087 to SFF 8088 cable? Will the total limit of 1m for SATA disks apply for this adapter also?

NO. They're fine for SAS disks, which run at much higher signal voltages, but do not use them for SATA, regardless of the cable length (contact resistance reduces the signal voltage enough where the set is extremely unstable).

The SFF-8087 to SFF-8088 cable solves this issue, so long as you keep the length to 1.0 meters.

 

[Jettbot]

Please note the cable length, as SATA is only rated at 1.0 meters (disk type that matters, even if it's actually a SAS card). SAS disks can go 10 meters due to much higher signal voltages.

Wow funny, just responded in a different thread you were also in.

I'm doing exactly what you describe with exactly the same cable from the same vendor. I'm going from a SAS internal card to an external SAS enclosure but populated with SATA drives. However I've ordered 2m cables from PC-Pitstop. Is that going to be an issue with the SATA drives? I was under the impression since they are getting their signaling from a SAS backplane it would not matter.

 

[nanofrog]

Wow funny, just responded in a different thread you were also in.

I'm doing exactly what you describe with exactly the same cable from the same vendor. I'm going from a SAS internal card to an external SAS enclosure but populated with SATA drives. However I've ordered 2m cables from PC-Pitstop. Is that going to be an issue with the SATA drives? I was under the impression since they are getting their signaling from a SAS backplane it would not matter.

You'll have problems with SATA disks at that length (have seen a few get away with ~1.5 meters, but not 2.0 meters - too much signal reduction = unstable).

So I'd suggest calling up pc-pitstop and changing the order before they ship it if at all possible. Otherwise, you'll have to explain you ordered the wrong length, and arrange a return for the right ones.