[CentOS] SSD for Centos SWAP /tmp & /var/ partition

Sun May 22 12:23:50 UTC 2011
yonatan pingle <yonatan.pingle at gmail.com>

On Sun, May 22, 2011 at 2:06 PM, Keith Roberts <keith at karsites.net> wrote:
> On Sun, 22 May 2011, yonatan pingle wrote:
>> To: CentOS mailing list <centos at centos.org>
>> From: yonatan pingle <yonatan.pingle at gmail.com>
>> Subject: Re: [CentOS] SSD for Centos SWAP /tmp & /var/ partition
>> On Sun, May 22, 2011 at 10:57 AM, Steven Crothers
>> <steven.crothers at gmail.com> wrote:
>>>> I was running on 3gbps sata bus, and the  performance was great, it
>>>> just dies in one big crash without  giving any clues about it.
>>> If only SSD's were a viable solution for long-term storage, we could
>>> theoretically increase our virtualization many times over. It's to bad
>>> the technology hasn't come far enough to be used that way though
>>> without costing an arm and leg.
> But it's going in the right direction now.
>>> --
>>> Steven Crothers
>>> steven.crothers at gmail.com
>> the only way to go with SSD is RAID due to these reasons.
>> it's unlikely that two disks will die at the same time, so it's
>> possible to use and enjoy them ,
>> but don't forget to have a fresh backup and a raid array. ( that
>> should be done also with an ordinary disk array anyways ).
> That's EXACTLY what I was thinking. Two 40GB SSD drives in a RAID array
> would not cost much at all. Move all the disk intensive stuff to that. I
> only have two root partitions of 20GB each for my main install - everything
> else is on other partitions on 2 x 500GB E-IDE drives. So putting the root
> partion on a small SSD (possibly RAIDed) is another option. Like most new
> electronics components, as time passes the mass production cost fall
> dramatically, and the technology improves. Look at the way HDD technology
> continues to advance.
> Maybe in 5 years time the cost of SSD's will be alot cheaper? Possibly in
> another 15 years time HDD's with moving parts will be consigned to history
> and science museums? I'm watching this technology very closely, and I'm very
> tempted to buy a small 40GB SSD like OWC's.
> They keep performing at optimal speed according to the specs for that drive.
> The OWC SSD's are supposed to have a MTTF of 2 million hours, PLUS they do
> not degrade over time. So if an OWC keeps going until MTTF, that's 24 x 365
> = 8760 HPY. 2000000 / 8760 = 228.31 years MTTF ?
> So why does it only have a 3 year warranty? - LOL
> For me anything on SWAP has to be better than a s/h drive thats had almost a
> years running time according to the SMART data on the drive:
> 9 Power_On_Hours  0x0032   090   090   000
>  Old_age   Always       -       7913
> 329 days running time already - let's see how long this one lasts before it
> kicks the bucket.
> Kind Regards,
> Keith Roberts
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I hardly swap to disk these days , and after the bad experience with
ssd as swap only ... i would stick to RAM & sata.

 RAM is so cheap , just get extra ram , and use PAE if 32bit (?)
adjust vm.swappiness ( sysctl ) to a lower value then 60 ( default ) ,
and you will be fine swapping on sata drives if and when needed.

if you are afraid of memory fragmentation , don't be .. in most cases
you will be rebooting the server when a new kernel update will come
out as it is....
the main question is , which kind of applications are you planning to
run on your machine, and what is your actual hardware *needs*, that
only you can tell.

also, for /tmp , you might like the idea of a ramdisk ( or tmpfs ) ,
it is a great way to speed up things without breaking the piggy bank.

this is what i use in /etc/fstab for my home desktop as /tmp :

/tmpfs               /tmp         tmpfs
size=512M,nr_inodes=5k,noatime,nodiratime,noexec 0 0

does the job well.

anyways - if it's for home usage  Don't think twice get an SSD .
Best Regards,
Yonatan Pingle