Which Cache Drive Should I Buy?

[geekette]

Looking for some recommendations for a cache drive, and why you think it's a good drive for this purpose.

 

Should I go for a 10k rpm SATA 6.0 gb/s?  How about a 15k rpm if there is such a thing for sata-6?

[Point7]

Any drive with write speeds >100MByte/sec will do just fine.  Your network speed is the bottleneck.

I've a 5400rpm 1,5TB cache drive and it is limited by the network speed (gigabit network) and i'm getting speeds around 100MB/sec.

[chickensoup]

The most important feature of a cache drive is how large to go and the answer to that question is; larger than the amount of data you intend to copy between moves. A larger drive however can also double as a "warm spare" incase you have another drive fail in which case you can sub your cache drive in until you get a replacement. If you run the mover every day and you copy ~200gb/day then a 250gb cache drive will suffice, a 500gb drive will give you more head room. If you do choose to go with a mechanical drive, a 7200/10Krpm drive would give you minor gains over a green drive.

 

As for speed; in most cases as Point7 stated the bottleneck is likely to be the network however if you really want to saturate your LAN and make sure when that your mover is running, your cache drive isn't holding you back then go for an SSD. They are by far the fastest drives you can buy but certainly not the most cost effective.

 

For more info I would recommend this topic (LOTS of useful information here):

http://lime-technology.com/forum/index.php?topic=5754.0

[Johnm]

For the average user... a cache drive the same size as your parity is recommended.

 

that way it can be used as a spare in case of a drive failure.

 

[Rajahal]

For more details on what chickensoup and Johnm are talking about, see this thread:

To Cache drive or not to Cache drive?

[chickensoup]

For more details on what chickensoup and Johnm are talking about, see this thread:

To Cache drive or not to Cache drive?

 

Same thread I posted the link to

[boof]

I'm leaning towards getting an SSD for my cache disk as I'm using it more and more for vm's (esxi datastore) and general application scratch space.

 

So basically not necessarily to help with network throughput but to speed up lots of random operations from multiple applications at once.

 

Is anyone running an SSD as their cache disk successfully? How has the longevity been - any issues?

[chickensoup]

I'm leaning towards getting an SSD for my cache disk as I'm using it more and more for vm's (esxi datastore) and general application scratch space.

 

So basically not necessarily to help with network throughput but to speed up lots of random operations from multiple applications at once.

 

Is anyone running an SSD as their cache disk successfully? How has the longevity been - any issues?

 

There are definately users on this forum using SSDs as a cache drive and it does make a noticable improvement. Though I doubt anyone has run them long enough to know how they will last and it would come down more to personal usage. An SSD in an unRAID server as a cache drive (under normal conditions) would have less I/O than in a regular desktop machine. I'm thinking about getting one to store the XBMC metadata (covers, synopsis, etc) as apparently that makes a big difference.

[darkside40]

There are definately users on this forum using SSDs as a cache drive and it does make a noticable improvement. Though I doubt anyone has run them long enough to know how they will last and it would come down more to personal usage. An SSD in an unRAID server as a cache drive (under normal conditions) would have less I/O than in a regular desktop machine. I'm thinking about getting one to store the XBMC metadata (covers, synopsis, etc) as apparently that makes a big difference.

That would also be my intention when using a SSD as cache drive. On the one hand speeding up trensfers when writing new media data to the array, on the other hand store artwork cache and sqlite db's of my Mediaportal PC's on the server to have a central database.

 

Also i would buy a rather small Cachedrive (eg. 64GB) and then let the mover run more often.

[chickensoup]

That would also be my intention when using a SSD as cache drive. On the one hand speeding up trensfers when writing new media data to the array, on the other hand store artwork cache and sqlite db's of my Mediaportal PC's on the server to have a central database.

 

Also i would buy a rather small Cachedrive (eg. 64GB) and then let the mover run more often.

 

As long as 64GB is large enough for your usage habits. I have a 150GB drive at the moment and if i replace it with an SSD I'll probably bite the bullet and get a ~240GB. Although it is more expensive it does save needing to play the data shuffle game at times. Even 120, 160 & 180GB SSD's are getting quite cheap though- the longer you wait the cheaper they'll get.. but thats the same with everything in the IT industry. It's never a good time to buy because there is always something faster and cheaper just around the corner

[Johnm]

As far as an SSD for a Cache Drive. I have been running SSD's for Cache drives for quite a while.

 

Here is what i noticed...

 

on my SATAII High Performance SSD's (Mushkin Enhanced Callisto Deluxe ), After a few weeks, it was slower then network speeds. the lack of trim was really gunking the drive up.. a 7200RPM drive was faster for plain writes. it dropped to about 85MB/s

 

on my SATAIII High Performance SSD's (OCZ Vertex 3), After a few weeks it also got all gunked up.. but, still wrote faster then network speeds. I could Peg the drive at 99% for the full size of the drive. (it still wrote at about 215 MB/s over 10GBe. it was closer to 520MB/s when trimmed)

 

In both cases, I could still have the mover running and get full sustained write to the server.

so, even a smaller SSD with the mover running every hour or 2 is still going to be a good cache drive.

just make sure it large enough to not be filled up between mover runs.

 

if you have a few extra bocks to spend, especially if you are considering running APPs on the SSD, look at this info http://lime-technology.com/forum/index.php?topic=14695.msg172789#msg172789

 

Running one of these 2 drives gets about 520+MB/s due to its auto garbage collection while in unraid.

 

 

 

 

 

 

[boof]

Thanks, very very interesting and good info.

 

Did you end up buying either of the SSDs you link to? Or did you end up with the vertex mentioned above instead?

[Johnm]

Thanks, very very interesting and good info.

 

Did you end up buying either of the SSDs you link to? Or did you end up with the vertex mentioned above instead?

 

I bought 2 of the Corsair Performance Pros. I used 1 for my ESXi datastore and one for the unraid Cache.

 

After a week or so like this, I moved both Corsairs into Datastore positions and put my OCZ back as a cache drive. I Plan to replace the OCZ as soon as I see a sale on the corsair or the plextor.

 

I will mention that the Corsair does get quite warm under constant use unlike all the other SSD's I'm used to.

[chickensoup]

IIRC Tom was looking at incorporating better SSD/TRIM support somewhere in the not too distant future (5.1ish?). I don't know how far down the line this is likely to be though. If the SSD becomes noticably slower over a period of time, a full zero of the drive should help pick the performance back up, correct?

[mrow]

I use a 7200rpm 320GB WD Scorpio Black. It's a 2.5 inch drive. I had a few lying around leftover from something at work. Because it's small and runs very cool naturally(never seen it get above 25 degrees), I just have it sitting on the bottom of my tower so it doesn't take up a slot in my 5in3 cages. I run the mover script daily so the storage space is not an issue.

 

http://www.wd.com/en/products/products.aspx?id=130

 

 

 

I actually have a SSD lying around too that I thought about using but until TRIM support is added I'm going to hold off.

[darkside40]

Wonders me that Trim should be so important, arent the Garbage Collection Algorythms of the SSD's not that good like the Manufacturers always tell us?

[Johnm]

Wonders me that Trim should be so important, arent the Garbage Collection Algorythms of the SSD's not that good like the Manufacturers always tell us?

 

read this http://www.xbitlabs.com/articles/storage/display/marvell-ssd_7.html

[c3]

Yeah, I changed the SSD in my MacBook after that.

[mrow]

Yeah, I changed the SSD in my MacBook after that.

 

Why? Lion has TRIM support built in and there's a utility out there to enable it in Snow Leopard.

[dikkiedirk]

As far as an SSD for a Cache Drive. I have been running SSD's for Cache drives for quite a while.

 

 

 

if you have a few extra bocks to spend, especially if you are considering running APPs on the SSD, look at this info http://lime-technology.com/forum/index.php?topic=14695.msg172789#msg172789

 

Running one of these 2 drives gets about 520+MB/s due to its auto garbage collection while in unraid.

 

You mean the Corsair or Plextor? Would SABNZB benefit from this?

 

Are SSDs nowadays suitable for repetitive read writes? How soon will a SSD wear-out in these conditions?

[bwall244]

^ I am interested in this also.

 

My plan was not to run a cache drive because write speed is not overly important to me. However I have read that I will have to if I plan on running sabznbd and sickbeard. A 500GB green drive is around $60 now, but so is a 128GB SSD. I would rather go SS to save on heat and power, but if it is going to wear out and not work, or slow write speeds to slower than a green drive then I've got a problem.

[marcusone]

If you need just an app drive an ssd formatted ext4 and mounted via the go file works well. Need v5 to do this.

 

Sent from my SGH-I727R using Tapatalk 2

 

 

[bwall244]

^That may have gone over my head a bit, I'll have to read up. If just for apps obviously I could go smaller than 128GB. Would there a a reason not to just go 128 and use it as a cache drive also? I'm planning on running the same CPU as your set up, I assume you have been pleased? What benefit do you see from the dual LAN mobo?

 

[BobPhoenix]

^That may have gone over my head a bit, I'll have to read up. If just for apps obviously I could go smaller than 128GB. Would there a a reason not to just go 128 and use it as a cache drive also? I'm planning on running the same CPU as your set up, I assume you have been pleased? What benefit do you see from the dual LAN mobo?

As a non-cache drive with EXT4 format you get trim support and the SSD will last longer.  Personally I would still get the 128GB SSD (if you choose to go SSD).  I always find I need more space then what I started with.  I'm sure you can find a use for it.  You could use it as temporary storage - sort of an offline cache drive for instance.  Then move the files from there to the array with your own mover routine.