SSD Questions

Hi There!

I am considering a move to SSD in my server to improve performance, but I am wondering about the following things.

I was going to put a 120GB Drive in as my c: and then move my SQL DB's and pagefile back there.  I know it will improve my boot time, but hopefully I shouldn't need that much, but it would be nice if it gave me a bump to the SQL DB Performances.. Small number of users  though so I know it's hard to say..

The other question was around reliability. I normally would mirror or R5 everything, but SSD's are more reliable, and we do keep backups, but I am wondering if I should RAID them or just not worry about it?

The server in question is a ML350G5 with 18GB and now I run 5 x 72GB in a RAID 5 with a Hot Spare.
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OCDanConnect With a Mentor Commented:
As others have said although SSDs are more reliable but you still need RAID in a production environment.

If you can afford it I would do RAID 5 again, especially if you want DB and Exchange on the same disks. SSD's have come down in price so much now that they pretty much the same price and often cheaper than comparable GB on SAS.

We have had SSDs running our SQL server for over a year now, and our DB is about 180GB and is used by 280users daily. What you should bear in mind when you talk about bad sectors is that they are not the same as in mechanical drives, a bad sector in them means exactly that. Whereas, on an SSD a sector just cannot be written to anymore, which means that you can always recover the data, you just can't write to it anymore

With over a year of use we don't have any sectors that cannot be written to, so depending how much use your disks get I don't think that is going to be an issue for you.

We are using a mix of 512GB Crucial M4 SSD and 600GB Intel 520 (in different RAID arrays).
SirjacksinurboxConnect With a Mentor Commented:
First, if you are going to move to an SSD as a boot drive, you don't need a pagefile anymore. You can disable it because your seek times are near instant on the SSD. Another reason to disable the pagefile, or at least not have it on your SSD is because it puts a ton of unnecessary read and writes onto it, which will drastically shorten its lifespan. Plus you're running 18GB of RAM. Even for a server with several DB's on it, you pretty much don't need one (unless a program you run on it specifies that a pagefile is necessary).

Second, if this is a production server; I would, without a doubt, RAID 1 the boot drive. Even if you have a backup of it, they downtime it will take to replace the drive and restore everything could cost you a lot of money. Two SSD's in RAID 1 will work great, and you will always have a running mirror.

For relaibility, I would look at the Intel line of SSD's. They have the lowest failure rate, and have a solid warranty. I use them in any of the corporate equipment that requires an SSD.

How big are the DB's and how many users are usually on it at any given time?
Yes, SSD are much faster and reliable then other drives but as this is server with database i will suggest to have RAID1 on the system without any question. SSD doesn't mean it H/w can fail it is just their is no moving part so their is less chances of crash. you can think of like we have memory failures in our system and SSD is just same like big memory cards.

Hope this helps.
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networknAuthor Commented:
Thanks. It's a small company, 5 people, accessing 4 DB's all about 1.5GB in Size.

I was also considering moving my mail system to it (Novell Groupwise) which is Disk IO Intensive with LOTS of small files.

Thanks for the tip on the PageFile, I'll disable it.

I wasn't really wanting to buy two of these SSD's but I'll look at the intel, I may be able to make do with a 60GB one since GW is 30GB and I have 10GB of Databases. 90GB if I want my OS on it.
Sounds good.

So ideally, you want to run the DB's on the SSD, as well as the mail system, correct?
i will refrain from disabling pagefile. pagefile is used for memory purpose and not just for disk I/O.
networknAuthor Commented:
Well ideally yes. I am now thinking perhaps I don't bother moving my OS to the SSD, just the mail server and DB's, and run a single, since the it won't be the entire server, just email and DB's to restore.

It used to be talked about that SSD's had a limited life of x number of write cycles per cell, and I am worried that the life of the SSD might not be ideal for Groupwise which has thousands of files being touched many times during each day..

Bad sectors could knock a sata drive or sas drive on it's backside, do the same concerns exist in SSD's? I know that say a 120GB drive keeps 8GB spare for bad "cells", but how seamless is it?
ideally it is much better then SATA HDD. and less concerns of bad sectors...
Yes, make sense to move the DB and mail server to the SSD which is the main performance during running of the servers.
CSIPComputingConnect With a Mentor Commented:
If this is a production server in a live environment, then please use RAID 1 as a minimum to protect your data in the event of a hardware failure.  Yes they're reliable, but given the cost of them vs time of 5 people sitting doing nothing whilst you recover email and databases because a drive has failed... It's a no-brainer!

You save £100 by ony using one drive.
You pay users £20/hour
Server drive fails at 10am on Monday.
You drive to the local shop and buy a replacement drive (30 mins)
You down the rest of the server, replace the failed drive and boot back up (30 mins)
You find the latest tape and start the restore (checking you've selected the correct items to restore) (30 mins)
You wait for the restore to happen (1h)
You bring the server back on line after post-restore checks etc (30 min).

You've just LOST £300 paying people to sit doing nothing - And that's a best case example.  What if it's an 8-hour restore?

Just my two pennethworth...
@Anuroopsundd: that may be true, but if your daily maximum use doesn't involve the use of at least 80% of your RAM, then its not practical to have a pagefile on the SSD. If
networkn intends to use the the SSD for just the DB's and mail, the pagefile residing on the boot drive would be ok. If everything is going to the SSD, then I would move the page file to the RAID 5 array.

@networkn: If your company can deal with the possibility of having a few hours of downtime if the SSD fails, go for the single. If you can get the extra money for the second ssd, don't hesitate. If the money people seem hesitant about forking over the extra money for two instead of one, just mention that scenario to them (the one with the downtime), and they should eventually give.

As far as the "bad cells": most, if not all, SSD manufacturers program fail safes for the data if a cell goes bad. You shouldn't notice any difference if there is one. Intel ships the ssd with a program to monitor the ssd drives health, just in case you want to check.

@ OCDan and CSIPComputing: You're preaching to the choir. I agree 100%. You have to have at least a raid 1. Depending on the size of the company and the projected scale of it, a raid 5 might not be a bad idea.

Those Intel 520's are amazing. We run one of those on a DNA sequencer with an NVIDIA card to crunch the numbers, and it completely blows everything else out of the water. I also run a 120GB 520 in my work laptop. Not complaints on the thing.
networknAuthor Commented:
Yah the problem with the RAID is that I would need to purchase another RAID Card, which puts the price up again, as the built in raid only works on the drives in the Hot Plug Bays.

I am horribly reluctant to use software RAID, I presume the same problems exist on a SSD with software RAID?

I get what you are saying about the additional drive though, I need to see what my options are.
OCDanConnect With a Mentor Commented:
I'm not familiar with your server but in our IBM x3350 M3 you can plug the SSD's straight in to the back plane with a bit of work to get them sitting properly.

Yes software RAID is a bad idea, the problems are exactly the same for SSD and I definetely would not recommend it.

Also on your RAID card is there only one input? e.g. from the back plane
networknAuthor Commented:
Yes only one input. I am actually thinking I might be able to fit one to a bay. I'll look on monday. Thanks
In a production environment like yours, hardware raid is really the only way to go. Software raids fall short every time and in every category. A hardware raid beats it hands down. Plus with software raids, your performance is only as good as your slowest bottleneck on the board.
A wise old owl said to me once:

"If it's worth doing, it's worth doing properly."

If you're considering putting a single SSD in, with no RAID, personally I'd not bother.  Same goes for any type of drive (other than floppy/CD of course)

A stand-alone Raid card, 2 x SSDs and a small amount of time will give you a massive boost in performance AND won't come back to bite you!
Anthony PerkinsCommented:
If you cannot afford using RAID with SSD, consider using your SSD for your tempdb database.  This should help performance tremendously.
CallandorConnect With a Mentor Commented:
An SSD would benefit a database tremendously - random access time is on the order of 0.1 msec, versus 8 msec for a regular hard drive.  The problem with hardware RAID is that no RAID controller supports TRIM, which is desirable to even out wear in SSDs.  You would have to live with garbage collection or go with a non-hardware RAID solution.

Software RAID with Win7 and Win2008 is actually a performance booster, since the OS does load balancing.  It is a recommended alternative when hardware RAID controllers are too expensive
Regarding the SSD life in your system, you can predict the average life time with this tool: Ssd ready.
networknAuthor Commented:
Hmm there are a lot of valid contributors to this discussion (Which wandered from the original topic because of additional questions I asked) Does someone want to suggest a points allocation?
You should accept the comment which best answered your question, and distribute points according to how the comments helped you.
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