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Samsung ships the world's highest capacity SSD, with 15TB of storage

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Re: Samsung ships the world's highest capacity SSD, with 15TB of storage

#11

Post by sdesol »

cm2187 wrote: post #6
NovaS1X wrote: post #2

Impressive. First question that pops into mind is how long the rebuild time would take if one of these failed in a RAID. I can imagine it'll take a while.

I thought RAID and SSD were a terrible combination. As if both drives do exactly the same writes at the same time, chances are they will fail at the same time. Plus most RAID controllers don't support TRIM. Has the thinking changed?

> I thought RAID and SSD were a terrible combination

Well there are different RAID settings. My product is an indexing engine (indexes Git repositories) and I've personally found RAID 0 reduces indexing time by about 30% compared to a single drive. I have a machine that has 4 SSDs running RAID 0 and I've found the performance gain after 3 SSDs is negligible.

It seems like 3 SSDs running RAID 0 is the best combination given my very limited sampling size.

Re: Samsung ships the world's highest capacity SSD, with 15TB of storage

#13

Post by [deleted] »

cm2187 wrote: post #6
NovaS1X wrote: post #2

Impressive. First question that pops into mind is how long the rebuild time would take if one of these failed in a RAID. I can imagine it'll take a while.

I thought RAID and SSD were a terrible combination. As if both drives do exactly the same writes at the same time, chances are they will fail at the same time. Plus most RAID controllers don't support TRIM. Has the thinking changed?

[deleted]

Re: Samsung ships the world's highest capacity SSD, with 15TB of storage

#14

Post by gfody »

cm2187 wrote: post #6
NovaS1X wrote: post #2

Impressive. First question that pops into mind is how long the rebuild time would take if one of these failed in a RAID. I can imagine it'll take a while.

I thought RAID and SSD were a terrible combination. As if both drives do exactly the same writes at the same time, chances are they will fail at the same time. Plus most RAID controllers don't support TRIM. Has the thinking changed?

Software RAID or a host-based controller is the way to go with SSDs. Otherwise the raid controller becomes your bottleneck as whatever onboard ASIC or RAID-on-a-chip hits its throughput limit (and potentially overheats and dies if it's some crappy product designed for HDDs).

TRIM is well supported by modern host-based controllers designed for SSDs.

Re: Samsung ships the world's highest capacity SSD, with 15TB of storage

#15

Post by Sanddancer »

cm2187 wrote: post #6
NovaS1X wrote: post #2

Impressive. First question that pops into mind is how long the rebuild time would take if one of these failed in a RAID. I can imagine it'll take a while.

I thought RAID and SSD were a terrible combination. As if both drives do exactly the same writes at the same time, chances are they will fail at the same time. Plus most RAID controllers don't support TRIM. Has the thinking changed?

They'll have the same lifespan, but they won't fail at exactly the same time. Also, a lot of RAID now is done in software, and most software raid types support TRIM.

Re: Samsung ships the world's highest capacity SSD, with 15TB of storage

#16

Post by stray »

chipperyman573 wrote: post #8
cm2187 wrote: post #6

Earlier quoted context omitted.

I thought RAID and SSD were a terrible combination. As if both drives do exactly the same writes at the same time, chances are they will fail at the same time. Plus most RAID controllers don't support TRIM. Has the thinking changed?

Yeah, the statistical chance of the same thing happening on both drives is the same, but the chance of it happening at the same time is pretty low.

That sounds perfectly reasonable, and 20 years ago I'd have said the same thing. It's even fairly likely that I did say it.

You know where this is going, right?

I was a SysAdmin at the time and one of the things I was responsible for was Oracle Financials. It was at the core of everything that mattered at that company -- and I was absolutely convinced that short of a water balloon fight in the machine room, my raid configuration was 100% reliable.

The first disk died late on Friday. I had two on-hand so I casually replaced it -- and before I got back to my desk another had died.

I placed an order for more drives and went back to the machine room and replaced it.

By Monday morning, things were starting to get serious -- I had to drop back to raid 5 because a few more had died over the weekend and my replacements wouldn't arrive till Tuesday.

You see, all the drives in all our raid enclosures had come from the same batch -- and they all -- every single one of them -- died within 90 days of the first one.

The chances may have been low, but reality has sharp teeth and loves the taste of overconfident sysadmin ass.

Re: Samsung ships the world's highest capacity SSD, with 15TB of storage

#17

Post by ars »

stray wrote: post #16
chipperyman573 wrote: post #8

Earlier quoted context omitted.

Yeah, the statistical chance of the same thing happening on both drives is the same, but the chance of it happening at the same time is pretty low.

That sounds perfectly reasonable, and 20 years ago I'd have said the same thing. It's even fairly likely that I did say it. You know where this is going, right? I was a SysAdmin at the time and one of the things I was responsible for was Oracle Financials. It was at the core of everything that mattered at that company -- and I was absolutely convinced that short of a water balloon fight in the machine room, my raid c…

> The first disk died late on Friday. I had two on-hand so I casually replaced it -- and before I got back to my desk another had died.

That happens very very very often. It has nothing to do with a bad batch.

The second disk actually failed a while ago, but no one noticed because no one read from that part of it.

When you did the rebuild you read from the failed area and woke up the failure.

When you setup raid you MUST read the entire raid at least monthly, so that any errors are detected early! This is absolutely critical. Without that you have not installed the raid correctly. mdadm on debian does that by default. Linux has a builtin way to do that, but you must have a tool that will alert you on failure, or it's worthless.

You should also run a week full disk read of each hard disk in the array using its onboard long self test feature. You can use smartd to schedule that automatically. And more importantly: Notify you on failure.

Not using both tools is not setting up the raid correctly.

Re: Samsung ships the world's highest capacity SSD, with 15TB of storage

#18

Post by jschwartzi »

imaginenore wrote: post #12
Animats wrote: post #9

It's awe inspiring to see fifteen terabytes of solid state storage in that little box.

It's still less dense than 200GB MicroSD cards. (which are only $79.50 on Amazon)

Does that density include the connectors and buses that would be required to access those cards?

Re: Samsung ships the world's highest capacity SSD, with 15TB of storage

#19

Post by guy_c »

stray wrote: post #16
chipperyman573 wrote: post #8

Earlier quoted context omitted.

Yeah, the statistical chance of the same thing happening on both drives is the same, but the chance of it happening at the same time is pretty low.

That sounds perfectly reasonable, and 20 years ago I'd have said the same thing. It's even fairly likely that I did say it. You know where this is going, right? I was a SysAdmin at the time and one of the things I was responsible for was Oracle Financials. It was at the core of everything that mattered at that company -- and I was absolutely convinced that short of a water balloon fight in the machine room, my raid c…

I wonder, for such mission critical data a good strategy would be to start rotating out old drives at set periods. Maybe replace one drive of your RAID5 every 6 months, not matter what the health. Once you've replaced all the drives, they will all be staggered in age by 6 months. Hopefully then the chances of multiple failures is greatly reduced.

Re: Samsung ships the world's highest capacity SSD, with 15TB of storage

#20

Post by jlgaddis »

cm2187 wrote: post #6
NovaS1X wrote: post #2

Impressive. First question that pops into mind is how long the rebuild time would take if one of these failed in a RAID. I can imagine it'll take a while.

I thought RAID and SSD were a terrible combination. As if both drives do exactly the same writes at the same time, chances are they will fail at the same time. Plus most RAID controllers don't support TRIM. Has the thinking changed?

I just (like, about the time you were writing your comment) replaced a pair of spinning disks with a pair of 120 GB SSDs in one of my machines here at home. It's not technically RAID but a ZFS mirror instead. The operating system and related files will live on it while my data still lives on some spinning disks (simply because of the amount of data).

I've got pretty much the same setup (albeit with several more spinning disks) in a bunch of servers and have yet to have any problems (* crosses fingers *).

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