NAS SSD Cache and Caching Benefits - Before You Buy

[Music] hello and welcome back and today i want to talk to you guys about ssd caching this is another before you buy and i want to give you guys five important things to bear in mind before going ahead and investing in ssds to improve your nas's performance because ssd cache is beneficial it is important and it will improve the read and write access and general return of data from your nas in a number of ways but in all the ways and a number of you may be on the verge of buying ssds to improve your nas and its performance and you're not actually going to see the benefits you're just throwing your money away so today i want to cover these five points and hopefully help you decide whether you should invest in ssds for your nasa reason number one that a number of you you know might or might not go for ssds in your nas is because the ssd caching system as it stands currently really only largely benefits random access of data on your now so what that means is if you're doing frequently accessed data on your system but smaller data that is more regularly accessed over and over again we are talking background metadata we are talking um any files we are talking config files we are talking thumbnails all those files are more regularly accessed maybe on a shared drive but not in a timely fashion and or kind of dotted all over the drives these are the ones that are going to see the benefit in the system of ssd cache and we will talk a little bit about the difference there of random and sequential in a bit but if you aren't accessing your nas in that way and you are dealing with big blocks of data pretty regularly you are not really going to see the benefit with those larger files and the way they are constructed and the data is laid out across the disk so do bear that in mind the ssd caching benefits those users in that fashion reason number two that you might or might not want to go for ssd caching is the ssd cache does not really support those large file types and i already touched on that just now but it's worth really zooming in on that point because a number of you will say oh get ssds to help me in my clex media server and there are benefits in the same way there are benefits to virtual machine utilization but bear in mind the big bulky image files the big bulky video video files they are not the ones that will see the benefit it's the smaller data the surrounding data and again the reason for that is to do with that difference between random and sequential so sequential data when it's read across the disk is a bunch of data that's all blocked together anyways when it's being accessed there is no inherent performance benefits it just goes for each part in the line there of the data now random read access across the disks is going to be all of this we're going over there to get the metadata we're getting the index data we're getting and all of this random data being accessed in all these different areas now big blocks of video data again i'm going to keep coming back to video um media streaming and stuff like that none of that access there is random it's purely sequential it's only the surrounding data so that you will feel the difference you'll know you'll notice the difference of pages loading up of metadata a lot quicker the layout of data may load that little tiny bit faster with all the difference being in near millisecond uh kind of intuitive feeling difference but not really measurable unless you measure over a grandiose scale so bear in mind that the benefits of ssd caching don't really target those users who are dealing with big files all the time and specifically media file watchers the next thing to bear in mind is the difference between the two kinds of predominantly used caching in nas read only and read and write cache there are other ones right only and stuff like that and right back and stuff but i'm going to lay off those a little bit because a lot of those go into the way the software on the nas interacts with it and different nas brands have their own varying range of ssd cache supported but these predominant two read only and read write cash are kind of the main two to go for so what are the different differences between them well let's focus on read-only cash first read only cash you can get away with a single ssd you can use a group of ssds and they will be put into a raid zero but you can get away with a single ssd read only cache is when you are interacting with the nas the data that you send to the nas is put on to the main hard drive storage array and then the frequently accessed files uh or background any files that sort of thing are moved onto the cache and then when you are accessing them from the nas you are drawing them from the cache as the system deems them appropriate enough to be moved on there for you to draw from them the result is if that ssd dies you're not going to lose anything because all that data was on the hard drives anyway and again it's more affordable but the benefits are only seen in the reading and of course not in the writing now with read write cash it's a slightly different scenario first and foremost you need to have at least two ssds and some systems support multiple which will be in generally a raid one environment you can kind of do it with a raid 5 but i would strongly recommend those two discs in a raid 1 environment because read write caching is when when you are sending data to the nas it passes through that cache on its way to the hard drive array there and again that is one of the main benefits of write cash it improves the performance of both write and read in the same way that read only did but one of the main main main reasons you need the two disks in a raid there because there is a chance very very small that as you write onto the cache if the cache fails due to the nand wearing out the interface dying or any one part of that the ssd dying you potentially lose that data that's going towards or it creates a corruption on the data which then moves on to the hard drives and that is why you need the two disks in the raids in the same way you'd have hard drives in a raid to protect yourself from those sort of events happening now of course read write cash is more expensive and read write cash will result in you having 50 of the capacity so two 1 tb ssds in a read-only cash will give you 2 tb two 1tb drives ssd drives in a read write cache will only give you one tv so two one bear in mind it's going to cost you twice as much to have that amount of cash capacity generally i would always recommend read write cash because you get the performance both ways and you've got that raid um fail safe there in case one of them dies next we can talk about the memory utilization of cash because in order to take advantage of ssd caching on your system it's not just about the hard drives and the cpu and the ssds you're checking inside you do need sufficient memory in the background to make sure that the cache is handled appropriately by the system ultimately you need the system resources to negotiate the cash whether that is the data being moved over to the read-only cash or to have the handling of data during the pass-through of that right cache there now uh one gig of ssd that's going to be utilized for cash will require 416 kilobits of memory so if you are looking at a 500 gig um ssd cache you're going to need about 203 204 megabytes of cash so again about a fifth of a gig of memory is required for 500 gig of cash and that doesn't seem like a lot but if you're running a nas that's got two gig of memory you're already gonna lose about three to four hundred meg generally from the ssd from the os on your nas running if you're gonna run flex media server you're gonna lose at least another gig there uh in general utilization so on a two gig nas two to three hundred meg for ssd caching is actually quite a big demand so make sure you take care of the fact that you've got enough memory before you go down the road of installing ssds for caching otherwise there will be insufficient memory to run the caching and your system will lag appallingly and ultimately you'll lose any benefit you were going to have of ssd caching the last point is one that i'm pleased to say is slowly going away but it's still out there and something you have to bear in mind now when you create an area of ssd caching be read only or read write caching bear in mind that this cache is going to be attached to a raid array your storage there of data and presenting its benefits to that area of storage but bear in mind it's a two-way street and the ssds whether you are going to convert them from two ssds in a read-only cache to a read-write cache or you're going to upscale them and replace them with new ssds maybe one is broken and you're replacing it apart from the very very very modern releases in say dsm-7 beta and some of the upgrades that have come to qts recently a lot of systems still require you to dismount the storage at the same time so if for example you are running a hard drive array there maybe got a raid 5 and you're supporting a few hundred shared users for home and business utilization and you've got caching there to support some of those shared drives and thumbnail generation stuff like that and config files in the background and you suddenly decide you know what i'm going to upgrade that ssd cache bear in mind if you dismount the ssd cache it will dismount the storage until the operation is completed now depending on the size of the ssds because they will wipe in advance they are sort of tying of loose ends between the hard drive storage array and the ssd cache the amount of time that that um storage array is offline does change between systems it could be anything from 15 seconds to 15 20 or even 30 minutes so if you're going to dismount the ssd cache for one reason or another bear in mind that a lot of systems will still dismount the storage for all the other users and they will it will sever all of their access there it will be reinstated and all the shares that were there before will be reinstated either after you upgrade the ssd cache or remove the ssd cache entirely but bear that in mind and with a lot of newer systems and again dsm seven beta here they did talk about how they're doing right back on the ssd cache so that the data is sent back when necessary bear in mind that it is still very prevalent on some systems that removing or configuring the ssd cache will dismount the storage albeit temporarily for quite a while for some of us but these are things to bear in mind if you're going to go down the road of ssd caching on your nands if you've got any further questions bang them there in the comments and if there's points i've missed and there's enough of them we'll do a follow-up video but otherwise click like if you've enjoyed the video click subscribe to learn more and visit the links in the description to learn more about the right way to pursue ssd caching on your nas i will see you next time

Channel: NASCompares

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Id: UE6xS0Rh7mo

Length: 11min 23sec (683 seconds)

Published: Fri Jan 22 2021