En tiempos de crisis describimos los puntos clave para diseñar una SAN de bajo coste.
- iSCSI
iSCSI es una alternativa a la clásica SAN de fibra óptica, siendo económica su implementación ya que no requiere de una infraestructura y tecnología adiccional Hardware de costosas HBAs y Switches de Fibra. Con sólo un switch ethernet ( o dos que aporten redundancia de acceso) y con un servidor con tarjetas Ethernet de Gigabit junto con unos discos ya tendrías una SAN. Los initiators y targets iSCSI en muchos sistemas vienen con la distribución, al igual que las soluciones de multicamino (multipath).
Existen otras alternativas a iSCSI también basadas en Ethernet como AoE (ATA over Ethernet) que al eliminar una capa de encapsulación de frames (IP) da mayor rendimiento.
- DISCOS
En la actualidad se diponen discos de buen precio y alta capacidad para una solución de bajo TIER. Un ejemplo podría ser 4 discos SATA de 3Gb/s , capacidad 2 TB, 64 MB de Caché y 7200 rpm con un total aproximado de 500€. Proporcionando aproximadamente unos 6 TB en RAID software con MDADM (solución de servidores Linux de RAID software) , que nos da una media de 111 euros por Tera tolerante a fallo (RAID).
Preguntadle a vuestro proveedor de SAN cuanto saldría una amplación de los TB en fibra … 😉
Aunque no es comparable una cabina de discos en fibra en cuanto a rendimiento debido a sus fenomenales características Hardware (tarjetas de fibra operando en modo target y procesadores dedicados, memoria caché del frontend y backend de los discos, …). Además sus discos tienen un rendimiento mayor, 15.000 rpm frente a los 7200 rpm que tienen los discos SATA, comparativamente pueden duplicar las I/Os y mejoras como gestión de colas o DIF T10. Según la necesidad de las aplicaciones del uso intensivo de disco podría ser adecuada una solución de bajo TIER.
- RAID
La tecnología RAID Hardware dejó de ser hace años exclusiva de entornos enterprise y cualquier placa de PC lleva integrado una controladora de discos SATA con soporte de RAID 0,1,5. Por otro lado los resultados del RAID por software (MDADM, ZFS, …) y los gestores de volúmenes (Logical Volumen Manager – LVM ,Solaris Volumen Manager – SVM ,Veritas Volume Manager – VxVM, ZFS, …) demuestran ser alternativa eficaz que complementan de forma segura y hacen flexible cualquier cambio posterior en el almacenamiento.
- MULTIPATH
Una solución SAN en iSCSI necesitaría de un switch ethernet para conectar los Initiator/s con los Target/s. Un diseño en SAN de fibra típico sería redundar HBAs y Switches de fibra proporcionando multicamino (multipah) al sistema eliminando puntos de fallo, se conseguiría de esta forma prevenir de cualquier fallo Hardware la continuidad de acceso a los discos. Esta tolerancia a fallos también es posible realizarse por analogía en iSCSI, redundando tarjetas y switches ethernet, acompañado de un software multipath propio de la distribución o usando nativamente el multipath iSCSI.
- SAN/NAS
Cualquier sistema UNIX/Linux dispone de soporte para protocolos fibra e iSCSI y combinar con cualquier protocolo de compartición de ficheros como SMB o NFS. Ésto nos permitiría crear un servidor que centraliza el almacenamiento en el CPD redireccionándolo a ethernet sobre protocolos de bloques (iSCSI) o de ficheros (SMB,NFS).
También existen soluciones enterprise con esta funcionalidad basadas en software abierto tales como NexentaStor, OpenFiler o FreeNAS.
- Sistemas de Ficheros con reservas
El acceso de diferentes servidores a los mismos volúmes (típico en clústeres) necesitan tener un control de acceso y reservas de forma que haya coherencia en las modificaciones en el sistema de ficheros. Ésto se puede conseguir eligiendo un sistema de ficheros de tipo disco compartido (Share Disk File System) como GFS (REDHAT) o VMFS (VMWARE).
- Controladoras Activo/Activo Activo/Pasivo
Soluciones software tipo IET en servidores linux sobre las tarjetas ethernet del servidor como Enterprise Target iSCSI proporcionará un comportamiento análogo al típico de las controladoras de cabinas de discos en fibra.
- Soporte
El tema más delicado ya que el soporte SAN va en función de la interoperabilidad entre fabricantes destacando los elementos siguientes:
Sistema Operativo – Multipath – HBA-Drivers – Switch – Almacenamiento – Modos del multipath
Y debido a que el diseño de cada elemento en su totalidad no se ajusta a los mismos estándares se necesita una certificación previa entre diferentes fabricantes.
Esta situación cambia bastante en un entorno iSCSI siendo un protocolo/estandar bien definido con una implementación precisa, que crea un marco de interoperatibidad mucho mayor.
Aún así, hablamos de la infrestructura que contiene los datos de una empresa, y si algo en su CPD debe de tener soporte es este almacén de datos. Por lo que el final de este diseño propuesto puede variar bastante si no se quiere contratar soporte … incluyento por ejemplo soluciones de backup, Alta disponibilidad (HA) con replicación síncrona entre dos cabinas de discos, … todo un tema a desarrollar y cuya implementación en producción es aconsejable que deba superar toda una fase de testeo intensivo y planes robustos de contingencia.
Lo aconsejable es buscar soporte en alguna solución tipo Openfiler, siendo una de las soluciones más flexibles que cumple los puntos propuestod … aunque no olvidar que hay que mirar la interoperabilidad con lupa y como ejemplo VMWARE no la certifica para sus servidores ESX.
Por otro lado si se elige una implementación de un target iSCSI sobre un sistema operativo, ésta solución no tiene porqué dejar de ser soportada por la distribución, ejemplo de ellos son: RHEL que incluye desde la versión 5.3 soporte para esta característica integrando SCSI Target Framework proyecto integrado en la linea principal de desarrollo del Kernel y mantenido por el creador de IET u OpenSolaris/Solaris Express 11 con el proyecto COMSTAR.
En Almacenamiento Abierto hemos diseñado cabinas de discos para entornos de producción con las siguientes características:
Ubuntu Server / SCST / LVM2 / MDADM (RAID 5) / HOT SPARE / ESX/ESXi 4/ MULTIPATH Nativo iSCSI/ SATA
Su aplicación para entornos de producción es un punto de interés fuerte por eso le hemos dedicado una serie de artículos sobre el proyecto SCST.
Si estás interesado en una implementación de targets SCST de bajo Tier certificado para VMWARE u otro entorno quizás te podamos ayudar, o si ya has implementado una o estás en en el proceso, nos gustaría conocer tu experiencia.
My brother suggested I might like this website.
He was totally right. This post actually made my day.
You cann’t imagine simply how much time I had
spent for this info! Thanks!
Asking questions are truly good thing if you are not understanding something completely,
however this post gives good understanding even.
Have you ever thought about publishing an e-book or guest authoring on other blogs?
I have a blog based upon on the same topics you discuss and would really like to have you share some stories/information. I know
my visitors would value your work. If you are even remotely interested,
feel free to shoot me an email.
Wow! After all I got a webpage from where I can actually get useful facts concerning
my study and knowledge.
Howdy, I think your blog may be having internet browser compatibility
problems. When I take a look at your website in Safari, it looks fine but when opening in Internet Explorer, it’s got some overlapping issues.
I just wanted to provide you with a quick heads up! Apart from that, excellent
site!
Hello it’s me, I am also visiting this website
on a regular basis, this website is truly pleasant and the visitors are really sharing
nice thoughts.
Thanks , I’ve just been looking for info approximately
this subject for a long time and yours is the greatest I’ve came upon till now.
But, what in regards to the conclusion? Are you certain about the supply?
For latest information you have to go to see the web and on internet I found
this website as a finest web site for most recent updates.
I blog quite often and I seriously appreciate your information.
Your article has truly peaked my interest.
I’m going to bookmark your site and keep checking for new details about once
per week. I subscribed to your RSS feed too.
You really make it seem so easy along with your presentation however I find this matter to be actually one thing which I feel I might by no means
understand. It sort of feels too complex and extremely
extensive for me. I’m having a look forward in your next post, I will attempt to get the hang of it!
Hi there, just became aware of your blog through Google, and found that it is truly informative.
I’m gonna watch out for brussels. I will be grateful if
you continue this in future. Many people will be benefited from your writing.
Cheers!
Hi there, I desire to subscribe for this web site
to obtain hottest updates, so where can i
do it please help out.
Everything is very open with a very clear description of the challenges.
It was truly informative. Your site is extremely helpful. Thank you for sharing!
Amazing! This blog looks exactly like my old one! It’s on a completely different subject
but it has pretty much the same layout and design. Great
choice of colors!
At this time I am going to do my breakfast, after having my breakfast coming yet again to read additional news.
This is the right webpage for anyone who wants to understand this topic.
You realize a whole lot its almost tough to argue with you (not that I personally would want to…HaHa).
You certainly put a brand new spin on a subject that has been written about for ages.
Great stuff, just excellent!
I visited various blogs but the audio quality for audio songs existing at this website is in fact marvelous.
Awesome blog! Do you have any suggestions for aspiring writers?
I’m hoping to start my own website soon but I’m a little lost on everything.
Would you recommend starting with a free platform like WordPress or go for a paid option? There are so many options
out there that I’m totally confused .. Any tips? Many thanks!
Thanks for one’s marvelous posting! I truly enjoyed
reading it, you may be a great author.I will always bookmark your blog and may come back later on. I
want to encourage one to continue your great posts, have a nice evening!
I’m excited to find this website. I wanted to thank
you for ones time due to this wonderful read!!
I definitely enjoyed every little bit of it and i
also have you book marked to see new things in your web site.
Remarkable! Its really amazing post, I have got much
clear idea about from this piece of writing.
What’s up, of course this paragraph is genuinely fastidious and I have learned lot of things from it concerning blogging.
thanks.
Hi there superb blog! Does running a blog such as this require
a great deal of work? I have virtually no knowledge of coding however I had been hoping to start
my own blog soon. Anyway, if you have any suggestions or tips for new blog owners
please share. I understand this is off topic however I just
wanted to ask. Thanks a lot!
When I originally commented I clicked the «Notify me when new comments are added» checkbox and now each time a comment is added I get three e-mails with the same comment.
Is there any way you can remove people from
that service? Thanks a lot!
Hmm it looks like your blog ate my first comment (it was super long) so I guess
I’ll just sum it up what I submitted and say, I’m thoroughly enjoying your blog.
I too am an aspiring blog writer but I’m still new
to everything. Do you have any recommendations for first-time blog
writers? I’d definitely appreciate it.
Very good article! We are linking to this great article
on our website. Keep up the good writing.
Hey there! This post could not be written any better!
Reading through this post reminds me of my good old room mate!
He always kept talking about this. I will forward this write-up to him.
Fairly certain he will have a good read. Many thanks for sharing!
My brother recommended I might like this web site.
He was once totally right. This submit truly made my day.
You cann’t believe simply how a lot time I
had spent for this information! Thank you!
Wow, awesome blog layout! How long have you been blogging for?
you make blogging look easy. The overall look of your web site is wonderful,
as well as the content!
Hi, i believe that i saw you visited my website thus i came to return the prefer?.I
am attempting to to find things to improve my web site!I suppose its adequate to use a few of your
ideas!!
Thanks for sharing your info. I truly appreciate your efforts and I
am waiting for your further write ups thanks once again.
Keep on writing, great job!
Hi there, its nice paragraph regarding media print, we all know
media is a enormous source of data.
Incredible! This blog looks exactly like my old one!
It’s on a entirely different topic but it has pretty much the same page layout and design. Superb choice of
colors!
Thank you for the good writeup. It in fact was a amusement account it.
Look advanced to more added agreeable from you! However, how could we communicate?
Good day I am so happy I found your weblog, I really found you by mistake, while I was researching on Yahoo for something else, Anyhow I
am here now and would just like to say thanks a lot for a marvelous post
and a all round entertaining blog (I also love the
theme/design), I don’t have time to go through it all at the moment but I have
saved it and also added your RSS feeds, so when I have time I
will be back to read more, Please do keep up the great job.
You need to take part in a contest for one of the highest quality sites
on the internet. I am going to highly recommend this web site!
I always spent my half an hour to read this weblog’s
posts daily along with a mug of coffee.
I always spent my half an hour to read this website’s articles daily along with a mug of coffee.
Hello friends, its fantastic article concerning tutoringand entirely explained,
keep it up all the time.
Hi there! This is my first visit to your blog!
We are a team of volunteers and starting a new project in a community in the
same niche. Your blog provided us useful information to work on. You have
done a marvellous job!
Hi all, here every one is sharing such know-how, so it’s
good to read this blog, and I used to visit this web site
every day.
This is my first time go to see at here and i am actually impressed to read everthing at alone
place.
You’re so cool! I do not think I’ve read anything like this before.
So wonderful to discover someone with original thoughts on this subject.
Really.. thanks for starting this up. This site is one thing that
is needed on the internet, someone with a little originality!
Great article, totally what I needed.
Oh my goodness! Incredible article dude! Thank you so much,
However I am encountering troubles with your RSS.
I don’t know the reason why I can’t subscribe to it. Is there
anybody getting identical RSS issues? Anyone that knows the solution will you kindly
respond? Thanks!!
Thanks for finally writing about > SAN de bajo coste | Almacenamiento Abierto
< Loved it!
Hello there! I could have sworn I’ve been to this website before but after checking through some of the post I realized it’s new to me.
Anyways, I’m definitely glad I found it and I’ll be book-marking and checking back frequently!
Thanks for the good writeup. It actually used to be
a enjoyment account it. Glance advanced to more added agreeable from you!
By the way, how could we keep up a correspondence?
Hey There. I discovered your blog using msn. This is an extremely neatly written article.
I’ll make sure to bookmark it and come back to read more of your helpful information. Thank you for the post.
I’ll certainly comeback.