Re: [ADMIN] 3 disks configured RAID 0 over 10 disks configured in RAID 5 (self replicating SAN)
Never RAID 5 for a database. When I say never, I can give you edge-case scenarios, but you're basically taking a 4x overhead on all writes. Now, RAID-0 is a bad choice as well, since JBOD has no replication, but it sounds like you might have that end under control. Original message From: Rene Romero Benavides rene.romer...@gmail.com Date: 08/27/2013 5:35 PM (GMT-06:00) To: pgsql-admin@postgresql.org Subject: [ADMIN] 3 disks configured RAID 0 over 10 disks configured in RAID 5 (self replicating SAN) Thanks for your attention. What would you choose for a postgresql installation: 3 disks configured with RAID 0 (in a self replicating SAN) over 10 disks configured with RAID 5 (also in a self replicating SAN) , we have space constraints that prohibit us from choosing RAID 1+0. I've been persuaded to choose RAID 5, because writes and parity computation will be spread over 10 disks compensating write overhead providing a better level of data security. Do you think it was a good decision? Any comment will be appreciated. Have a good day. -- El genio es 1% inspiración y 99% transpiración. Thomas Alva Edison http://pglearn.blogspot.mx/
Re: [ADMIN] 3 disks configured RAID 0 over 10 disks configured in RAID 5 (self replicating SAN)
Does your controller support odd number RAID-10 i.e. RAID 1E? If so then 3 disks in RAID-1E. Or better 10 disks in 1E On Tue, Aug 27, 2013 at 4:33 PM, Rene Romero Benavides rene.romer...@gmail.com wrote: Thanks for your attention. What would you choose for a postgresql installation: 3 disks configured with RAID 0 (in a self replicating SAN) over 10 disks configured with RAID 5 (also in a self replicating SAN) , we have space constraints that prohibit us from choosing RAID 1+0. I've been persuaded to choose RAID 5, because writes and parity computation will be spread over 10 disks compensating write overhead providing a better level of data security. Do you think it was a good decision? Any comment will be appreciated. Have a good day. -- El genio es 1% inspiración y 99% transpiración. Thomas Alva Edison http://pglearn.blogspot.mx/ -- To understand recursion, one must first understand recursion. -- Sent via pgsql-admin mailing list (pgsql-admin@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-admin
Re: [ADMIN] 3 disks configured RAID 0 over 10 disks configured in RAID 5 (self replicating SAN)
First of all, thank you so much for your valuable time. It probably does, though we have a requirement of having available at least twice the expected database size, and 50% of disk space overhead sounds like too much for us to take in a replicated SAN environment and a PostgreSQL master/slave - streaming replication setup. our options regarding disks availability at the moment are: a 3 disks array dedicated for PostgreSQL in any RAID configuration we'd like OR a 10 disks array shared with 14 virtual machines running the middleware layer and the application infrastructure in a RAID 5 configuration again, I do really appreciate your kindly help. 2013/8/28 Scott Marlowe scott.marl...@gmail.com Does your controller support odd number RAID-10 i.e. RAID 1E? If so then 3 disks in RAID-1E. Or better 10 disks in 1E On Tue, Aug 27, 2013 at 4:33 PM, Rene Romero Benavides rene.romer...@gmail.com wrote: Thanks for your attention. What would you choose for a postgresql installation: 3 disks configured with RAID 0 (in a self replicating SAN) over 10 disks configured with RAID 5 (also in a self replicating SAN) , we have space constraints that prohibit us from choosing RAID 1+0. I've been persuaded to choose RAID 5, because writes and parity computation will be spread over 10 disks compensating write overhead providing a better level of data security. Do you think it was a good decision? Any comment will be appreciated. Have a good day. -- El genio es 1% inspiración y 99% transpiración. Thomas Alva Edison http://pglearn.blogspot.mx/ -- To understand recursion, one must first understand recursion. -- El genio es 1% inspiración y 99% transpiración. Thomas Alva Edison http://pglearn.blogspot.mx/
Re: [ADMIN] 3 disks configured RAID 0 over 10 disks configured in RAID 5 (self replicating SAN)
On Tue, Aug 27, 2013 at 7:18 PM, Rene Romero Benavides rene.romer...@gmail.com wrote: First of all, thank you so much for your valuable time. It probably does, though we have a requirement of having available at least twice the expected database size, and 50% of disk space overhead sounds like too much for us to take in a replicated SAN environment and a PostgreSQL master/slave - streaming replication setup. our options regarding disks availability at the moment are: a 3 disks array dedicated for PostgreSQL in any RAID configuration we'd like OR a 10 disks array shared with 14 virtual machines running the middleware layer and the application infrastructure in a RAID 5 configuration again, I do really appreciate your kindly help. Whatever you do do NOT put postgresql on a RAID-5 array if you can help it. Can you steal a few disks for a 4 or 5 disk RAID 1E? -- Sent via pgsql-admin mailing list (pgsql-admin@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-admin
Re: [ADMIN] 3 disks configured RAID 0 over 10 disks configured in RAID 5 (self replicating SAN)
In your case I'd go for the 3 disk raid 0 setup. El ago 27, 2013 11:25 p.m., Scott Marlowe scott.marl...@gmail.com escribió: On Tue, Aug 27, 2013 at 7:18 PM, Rene Romero Benavides rene.romer...@gmail.com wrote: First of all, thank you so much for your valuable time. It probably does, though we have a requirement of having available at least twice the expected database size, and 50% of disk space overhead sounds like too much for us to take in a replicated SAN environment and a PostgreSQL master/slave - streaming replication setup. our options regarding disks availability at the moment are: a 3 disks array dedicated for PostgreSQL in any RAID configuration we'd like OR a 10 disks array shared with 14 virtual machines running the middleware layer and the application infrastructure in a RAID 5 configuration In your case I'd go for the 3 disk raid 0 setup. Be sure to have your failover scripts tested. Regards, Fernando
