SSD (Solid State Drive) and pfSense (Important)
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I've done a lot of reading on SSDs and my understanding is that when NAND flash blocks fail due to excessive writes they become read-only, and that early total drive failure is probably a different defect not caused by excessive writes. Even with a worst case scenario (3000 write-limit, 3x write-amplification) the numbers say you should be able to write more than 8 TB to the 8 GB Kingston S100 before it's used up. Even logging 2 GB a day the drive should be useable for 10 years.
Logging and, presumably, graph generation are sequential and the write amplification should be close to 1. Even swapping is mostly sequential.
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SSD vs SDHC vs FD vs CF
Do you really need the extra speed of a SSD or would a cheap SDHC card work great? Why are there many who run CF cards, but hardly any who use FD (flash drive) or SDHC cards? Is the SSD solely for the reliability over CF and SDHC?
Just curious, since I am deciding on what I will use when I build a pfsense box.
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You need to use something the motherboard can recognize as a bootable device. A lot of popular embedded hardware is still CF based.
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CF supports IDE directly, with a purely passive adapter, so it can easily be used in place of a hard drive. That's why it's present on many motherboards intended for embedded applications.
Steve
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Just as a follow up on the original topic on SSD drives and pFsense. Even with a RRD logging or a ton of packages installed pFsense does not write enough data to cause modern SSD's to fail due to write wear. I think many of these early failures are just do to it being such a new technology and they are being rushed to the market because it's new hot technology.
And since they're solid state, they tend to just fail abruptly unlike traditional mechanical drives. -
SSD vs SDHC vs FD vs CF
Do you really need the extra speed of a SSD or would a cheap SDHC card work great? Why are there many who run CF cards, but hardly any who use FD (flash drive) or SDHC cards? Is the SSD solely for the reliability over CF and SDHC?
Just curious, since I am deciding on what I will use when I build a pfsense box.
SDHC is horrible and slow! Absolutely use CF instead!
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I am trying to understand how pfSense handles disk I/O on a normal install. I run it as a guest in ESXi thus it is easy to monitor the amount of writes given a period of time:
As you can see, on average, there is a 24 KBps write rate to local drive.
What is causing these writes? I always presumed that even the normal image would try to do as much in ram as possible.
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SSD vs SDHC vs FD vs CF
Do you really need the extra speed of a SSD or would a cheap SDHC card work great? Why are there many who run CF cards, but hardly any who use FD (flash drive) or SDHC cards? Is the SSD solely for the reliability over CF and SDHC?
Just curious, since I am deciding on what I will use when I build a pfsense box.
Cheap SDHC cards are generally slower than CF cards of the same price bracket.
Also, SDHC cards will almost definitely need an active converter that costs more than their CF counterparts.
e.g. An SD to Sata covertor costs ~US$14 - US$20 whereas a CF to SATA converter costs ~$3 - US$4.00.CF is also compatible with IDE so a passive convertor (CF to PATA) can be had for a much lower price. Typical online price from a wholesale site like Dealextreme would probably cost you US$2.40 inclusive of international shipping.
I've ran pfSense on thumbdrives in production environments before. They work albeit slower than a CF-SATA and there were other issues to take care of (I had to hack the loader.conf to add the delay for mounting USB devices back then). In general, I've had better luck with CF cards compared to thumbdrives in terms of reliability as well.
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Hi,
I've beed using Industrial CF cards and SSD drives since about 10 years for industrial automation and routers/NAS and never had write issue… you are talking about 10000 writes this is strange because every datasheet I read are talking about 10 000 000 writes. Don't know which models you are using but they must be very cheap...
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damn.. I just found this thread. I guess I need to replace my 128GB SSD to regular HDD in my pfsense box before it fails.
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Almost certainly you don't. There is a huge amount of misinformation and paranoia in this thread.
Steve
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SSD drives are too expensive when you need only to write some log and RRD informations, use CF cards :
http://www.memorydepot.com/ssd/listcat.asp?catid=icf4000
2 000 000 writes/erases
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I agree with this.
The reasons you might want to use an ssd in pfSense are: heat, power consumption and reliability. In no particular order. However in all of those usage cases you would use the smallest drive necessary. The only time you might use something larger is for a fast squid cache; I have yet to form an opinion on that. ;)Steve
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Why not use disks from INNODISK??
They have DOM that sits directly in a SATA port. You can even get them in IDE. Very easy and stable.
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I am trying to understand how pfSense handles disk I/O on a normal install. I run it as a guest in ESXi thus it is easy to monitor the amount of writes given a period of time:
As you can see, on average, there is a 24 KBps write rate to local drive.
What is causing these writes? I always presumed that even the normal image would try to do as much in ram as possible.
See these two topics:
http://forum.pfsense.org/index.php/topic,52622.0.html
http://forum.pfsense.org/index.php/topic,52887.0.htmlMy system was short term averaging anywhere between 10KB/s and 25KB/s
I found a lot of writes were going to filter.log, in particular it was IGMP traffic being logged. If you don't need to do any filter logging, removing filter.log is a hacky workaround, but it needs to be re-applied every time the system is rebooted (cron + a reboot entry should be fine, I do it manually). I still have an average 2KB/s write going on in the background which I haven't been able to find the source of, so I plan to move to the embedded version because I am paranoid (and my SSD is a cheap MLC, rather than SLC).
Why not use disks from INNODISK??
They have DOM that sits directly in a SATA port. You can even get them in IDE. Very easy and stable.
The Innodisk SATA drives look very nice, I didn't know of a SATA variant before I bought my hardware, otherwise I would have got one. Nice reference for the future. Thanks!
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SSD drives are too expensive when you need only to write some log and RRD informations, use CF cards :
http://www.memorydepot.com/ssd/listcat.asp?catid=icf4000
2 000 000 writes/erases
the thing is I use this box also for squid + dansguardian. The performance is very good using SSD. I guess I need to move the squid + dansguardian to another box and replace the SSD with HDD or CF card. 128GB on pfsense without squid is waste of space, better place the SSD on my desktop machine.
I was going to get smallest SSD listed on local store but they only got the 120GB and up :( Regarding industrial CF card you linked, I don't think its available locally here in Indonesia :( I also tried to get sata to CF adapter but I couldn't find it. The closest I could find is USB to CF adapter.
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I read this topic and have doubts. I have SSD OCZ Vertex 4 drive and just installed livecd version of pfSense 2.1
I really need at least 2 packages:- freeradius,
- squid
- vpn
- log everything I can,
- create graphs by Sarg / Lightsquid.
Simple question now - should I change SSD to HDD?
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I read this topic and have doubts. I have SSD OCZ Vertex 4 drive and just installed livecd version of pfSense 2.1
I really need at least 2 packages:- freeradius,
- squid
- vpn
- log everything I can,
- create graphs by Sarg / Lightsquid.
Simple question now - should I change SSD to HDD?
I would think that in general: no.
Your OCZ Vertex 4 is at least 64GB, unless you're caching for a huge number of people, you shouldn't be wearing out your SSD with pfSense. You have, likely, a huge amount of room for wear leveling, you should be fine. A lot of people were seeing their problems in smaller drives with less robust (or simply not effective) wear leveling.
A Hard Drive will eventually fail; exceptions aside, expect high failure rates after 3 to 5 years, no matter how they're used (exceptions include: defects, high numbers of spin up/down cycles, temperature, vibration, etc.)
Defects aside, an SSD usually lasts until it runs out of cells to swap in for failed cells. The more free space the drive has to easily institute wear leveling, the larger the pool of cells it has to swap with. Many modern drives can also shift data that's been sitting on a cell for a long time and move it to an highly exercised, but still good cell to reclaim more underutilized cells to level with.
Now, you're using an OCZ drive, some of which are arguably more fail prone than some other brands. But, if it hasn't so far, it's probably fine.
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SSD drives are too expensive when you need only to write some log and RRD informations, use CF cards :
http://www.memorydepot.com/ssd/listcat.asp?catid=icf4000
2 000 000 writes/erases
I just had a hard drive failure a few days ago and the replacement hard drive I had already has been powered on for 5 years. The question is not if it will fail again, but when will it fail? After 5.1 years powered on? 6? Maybe 7? Anyways however you look at it, it's getting towards the end of that bathtub curve. So I want an SSD in there. And since this isn't for a hobby or my home (where I bought an 8GB Kingston SSD that had the WORST possible reviews ever… actually been very reliable, but the model's not sold any longer)
Many systems today no longer have IDE ports. And last time I tried this the SATA adapater was not very reliable. On cold boot I would have to boot the system and then press the reset buton for the CF to be picked up. Otherwise it gets stuck on "No boot device" error. Not very good at all. For this reason I would rather have a single unit from a known/reliable vendor. I was thinking of purchasing something like "Western Digital SiliconDrive A100 8GB MO-297 SATA II SLC Industrial Solid State Drive SSD-S0008SC-7100."
SSD drives are too expensive when you need only to write some log and RRD informations, use CF cards :
http://www.memorydepot.com/ssd/listcat.asp?catid=icf4000
2 000 000 writes/erases
the thing is I use this box also for squid + dansguardian. The performance is very good using SSD. I guess I need to move the squid + dansguardian to another box and replace the SSD with HDD or CF card. 128GB on pfsense without squid is waste of space, better place the SSD on my desktop machine.
I was going to get smallest SSD listed on local store but they only got the 120GB and up :( Regarding industrial CF card you linked, I don't think its available locally here in Indonesia :( I also tried to get sata to CF adapter but I couldn't find it. The closest I could find is USB to CF adapter.
I'm running HDD with Squid + Squidguard. I'm thinking it should run just fine using SSD embedded with a null/no cache.
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I'd get something larger. That way there is more unused space and the wear will spread out over the rest of he drive (not to be confused with reserved area). If you want long term, get larger even if you don't use it all.
Also SSD's are not 100% tried and true like HDD. It's also about history of the brand/model.
