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I want to build a server hosting about 2TB+ data. Of course SSD is out of the picture in terms of the data drive. My question is: Is there any benefit to use SSDs as the boot drive? I plan to put 16G memory on it. I think most of the time the services should be loaded in memory and the server should rarely require rebooting. In this case, does it make sense to get SSD or just get a RAID1 with two SATA drives?

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Optimizing the boot disk probably isn't worth it if you don't plan to reboot several times per day. Spend the $$ on more ram and avoid the fragility of current SSD's. –  Josh May 25 '11 at 3:39
    
Just go with a pair of 15k SAS drives in RAID-1 for the system drive. (Pretty standard in the hosting industry) –  Doug May 25 '11 at 13:37

7 Answers 7

up vote 9 down vote accepted

I don't think so, not at this time. They're expensive, it's a relatively new technology that's not without its own problems; Jeff Atwood has an interesting blog post about the advantages and disadvantages of using them.

Given your intended use case the need for an SSD seems even smaller. You normally see huge benefits when booting and when opening up apps, but on a data server with a lot of RAM that rarely gets rebooted there's no point in spending the extra money.

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In that post, Jeff reiterates what I've heard many times. That the failure rate of SSD's is very high. I wouldn't trust that on a server when you can get similar performance from noisy power-hungry disks since it's gonna be locked in a server room anyhow. –  Josh May 25 '11 at 3:36
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Jeff's talking about consumer grade SSDs. If you use consumer SSDs, you get what you pay for! There were also early problems with the X25-M's that may account for the failures mentioned there. We've deployed several hundred X25-Ms as OS disks in server systems since 2009 and have had a very low number of failures (single digit). We've deployed similar numbers of the Intel X25-e and had a similarly low number of failures. I don't dispute that Jeff and his friend have seen problems, I'm just giving you a broader set of data. –  Daniel Lawson May 25 '11 at 5:02
    
My other comment notwithstanding, I generally agree that without other mitigating reasons such as power or physical space, SSDs for boot drives on servers just don't make sense. I use them because I don't want to waste a spinning disk slot on the OS disk - we can put the SSDs elsewhere in the chassis. –  Daniel Lawson May 25 '11 at 5:05

It depends on the kind of server, but generally speaking, yes, it should be a good idea.

SSD drives are best for read-only data, which is usually what servers are as opposed to workstations. So it has that going for it.

Also, the faster a file can be served, the better the server will be, and since SSD drivers are supposed to be faster, it has that going for it as well.

Finally, SSD drives usually use less power, make less noise, and generate less heat, so the server will require less electricity and cooling (which are the banes of server-rooms the world over), so it has that going for it too.

That said, again it depends on the specifics of your server and case-usage (eg, 16GB sounds good, but will the files be cached in RAM or have to be fetched from disk anyway?), as well as the actual drives in question. Overall however, yes, most servers are generally better off with SSD drives.

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+1 good summary. one of the pro's is good random/parallel read performance as measured in the uFLIP paper –  mbx May 25 '11 at 11:40

With this situation, an SSD boot drive will probably only improve boot time, once everything is started and in RAM (you have 16GB) it won't make any difference. Maybe if you kept a 10GB+ database on it it might help, but probably better to spend the money on more magnetic drives (possibly for redundancy).

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I attended an Intel conference about a week ago; the Intel rep shied away from recommending SSDs for databases, at least at this point in time. –  alex May 24 '11 at 21:46
    
Yeah, I think particularly if your DB has a high amount of writes (iirc reads dont "wear" the SSD as much/at all), and performance with small blocks can be less than stellar. –  Spectre May 24 '11 at 21:50
    
@alex: There are plenty of companies who will sell very expensive SSD solutions designed for databases and they guarantee the results. Some people have been able to replace 30 servers with one. It's like going from disks to memcached. –  Zan Lynx May 25 '11 at 4:46
    
@Zan totally agree with you. Not all "sales-man" know how to implement all the possible solutions. –  Carlos May 25 '11 at 8:42

I think that's a good idea. The SSD promises greater reliability (especially important for laptops) and improved performance (no relative track-to-track seek time concerns), both of which are wonderful advantages when dealing with server problems.

Do keep in mind, however, that SSD is still very new and not immune to failures of its own. You should research the types of problems people are experiencing with different brands and models of SSD drives before going down this path.

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Depends on the server usage, from what you describe probably not worth it. Where SSD's come into thier own is servers with high I/O usage like virtual server hosts.

Stick about 10 virtual machines on a server with standard drives and then compare it to one with SSD's. Get all 10 VM's doing something and watch the SSD based server fly while the old magnectic drive one has stalling VM's as they wait for thier turn to read/write to the HD's.

Back to your original question though, why are you worried about the boot time? Are you planning on regulary rebooting the server? I have servers that haven't been rebooted for about 3 years which I would have thought would be reasonably normal for stable machines that just do the job they were supposed to do.

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That's a bad idea. SSD drives give you insane iops, and that's why you pay for them: to hold data that's accessed most frequently in a random fashion. A database on a set of SSD drives can outperform (especially for read-intensive scenarios) a very expensive storage system.

Operating system boots, then practically all executables that are used are kept in RAM, everything unused is put to swap. If you plan for heavy swap use (bad idea) you could put your swap on SSD, but I'd rather use a HDD and put the difference into RAM.

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I think it doesn't worth it most of the time.

But if you've got big computing requirements with big files (say Dailymotion / YouTube encoding videos) the read/write speed is probably important.

If your applications are doing a lot of reading, even small files, it can really boost up the performance. However, if you cache the most served data in RAM (See memcached daemon) this is not an issue anymore.

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